Your laptop has the final say, not the dock
It's tempting to blame the dock when a second screen stays black, but the dock can only pass along the video your laptop is willing to produce. So the honest place to start is the laptop itself, where two things decide what is even possible before any setting comes into it.
The first is whether the USB-C port carries video at all. Not every USB-C port does: as Anker's own dock guide puts it, "if your laptop's USB-C port does not support DisplayPort Alt Mode or Thunderbolt, it may not detect a monitor through the docking station". Anker suggests checking the icon beside the port, where a Thunderbolt lightning bolt or a DisplayPort "D" marker points to video, but plenty of USB-C ports carry no marking at all, so your laptop maker's specification page is the certain answer. Our explainer on which USB-C cables and ports carry video goes into that side properly; the short version is that a port with no video capability won't light a screen no matter which dock you plug into it.
The second is how many external displays the laptop is built to drive. A dock can offer two or three video outputs, but it can't invent display engines the laptop doesn't have. Anker notes plainly that "some laptops can only drive one external display through USB-C or Thunderbolt", so if one monitor works and the second refuses, the dock may be doing everything right and simply running into the laptop's own ceiling. The place to confirm it is your laptop maker's specification page for your exact model, which states how many external displays it supports, and it's worth reading before you assume the dock is faulty.
The DisplayLink question: a dock that needs its own driver
There are two different ways a dock gets a picture onto your screen, and they fail for different reasons. Most docks pass the video straight through from a DisplayPort Alt Mode or Thunderbolt port, so the laptop's graphics do the work and no extra software is involved. The other kind uses DisplayLink, which is a driver-based approach: the dock turns the display into data over ordinary USB, and a piece of software on the computer turns it back into a picture. Synaptics, which makes DisplayLink, describes its DisplayLink Manager as the app that "combines our latest driver" and lets you "enable your DisplayLink dock, adapter or monitor".
The practical consequence is simple. A DisplayLink dock shows nothing on the extra screen until that driver is installed, and Anker lists "DisplayLink software, if your dock uses it" among the things to install when a dock is not detecting a monitor. So if you've ruled out the laptop's own limits and the screen is still dark, check whether your dock is a DisplayLink model, which the box or the product page will tell you, and install the current driver from the dock maker or from DisplayLink directly. It's the one fix that resolves an entire class of dead-monitor cases outright.
The ordinary checks, in the order worth doing them
Once the laptop and the driver are sorted, the familiar checks are quick, and they do catch real cases. They just belong second, not first. Start at the monitor itself: a screen will sit on a blank input even when the dock is sending a perfectly good signal, so open the monitor's own menu and, in Anker's words, "select the input that matches the cable connected to your dock, such as HDMI 1, HDMI 2, DisplayPort, or USB-C".
Then look at how Windows is arranging things. If the monitor is detected but mirroring your laptop rather than extending the desktop, press Windows and P and choose Extend; Anker makes the same point, that you should "make sure the dock supports dual extended display mode" when you want separate content on each screen. If Windows isn't seeing the monitor at all, you can force it to look again: Microsoft's own guidance for a docked monitor that stays black is to "use the keyboard shortcut Win+Ctrl+Shift+B" or to open Display Settings and "click the Detect button". Updating the laptop's graphics driver belongs in the same group, since an out-of-date display driver can drop a screen that would otherwise work.
If none of that moves it, power-cycle the dock properly rather than just unplugging the laptop. Anker's sequence is to "unplug the docking station from your laptop", "disconnect the monitor cables from the dock", "unplug the dock's power adapter from the wall outlet" and "wait 30 to 60 seconds", then reconnect everything. A full reset clears the handshake state that a quick replug leaves behind.
When it is the dock's own ceiling
A dock has a rated monitor count and a maximum resolution and refresh rate, and asking for more than it was built for leaves a screen blank or quietly capped. A dock sold for two 4K screens won't light a third, and a dock rated for 4K at 60Hz won't run a monitor faster than that even if the monitor can. None of it is a fault; it's the specification doing exactly what it says. The figures are on the dock's own listing, and matching them to your monitors, and to your laptop's limit from the first section, is what tells you whether the setup was ever going to work.
If you're still choosing a dock and want one sized for your desk, our best USB-C docking station guide covers the picks, and if you're not sure whether you need a full dock or a compact hub at all, our hub versus docking station explainer settles that first.
FAQ
Q: Why won't my docking station detect my second monitor? A: Work through it in order. First the laptop: the USB-C port has to carry video, meaning DisplayPort Alt Mode or Thunderbolt, and the laptop has to be built to drive that many external screens, since Anker notes some laptops drive only one over USB-C or Thunderbolt. Then the dock's software: a DisplayLink dock needs its driver installed before the extra screen appears. Only then the quick checks, meaning the monitor's input source, Extend rather than Duplicate, forcing Windows to detect the display, and a full power-cycle of the dock.
Q: Does my laptop limit how many monitors a dock can drive? A: Yes, and it's the limit people reach for last. The constraint lives in the laptop's graphics rather than the dock, so extra video outputs on the dock can't conjure a screen the laptop was never built to drive. Anker states that "some laptops can only drive one external display through USB-C or Thunderbolt". Check your laptop maker's specification page for your exact model to see how many external displays it supports.
Q: What is DisplayLink and do I need its driver? A: DisplayLink is a driver-based way to add screens: instead of sending video straight from the port, the dock sends it as data over USB and software rebuilds the picture. Synaptics describes its DisplayLink Manager as the app that enables the dock and combines its latest driver, so a DisplayLink dock shows nothing on the extra monitor until that driver is installed. If your dock is a DisplayLink model, install the current driver from the maker or from DisplayLink before anything else.
Q: My dock detects one monitor but not the second, what now? A: That pattern usually points at a limit rather than a fault. Either your laptop drives only one external display, which its specification page will confirm, or you've exceeded the dock's own rated monitor count. Check both figures, then make sure the second monitor is on the right input and that Windows is set to Extend rather than Duplicate.
Q: The screen is black as soon as I dock, any quick fixes? A: Set the monitor to the input your dock's cable uses, then force the system to re-detect the display, which Microsoft suggests doing with Win+Ctrl+Shift+B or the Detect button in Display Settings. If it's still black, power-cycle the dock: unplug it from the laptop, disconnect the monitors, remove its power for 30 to 60 seconds, then reconnect.