Had to use an HDMI to DisplayLink adaptor. Cannot get any video signal (and the monitor says “no signal”) through the HDMI. My intel graphics says there’s only two monitors when there are now the laptop and two additional monitors.
Thank you for posting, and I would be happy to help with your docking station!
Based on your description is sounds like you are using a HDMI to DisplayPort cable or adapter to connect your monitor to the dock. This cable or adapter is a passive device that is only meant to work in one direction, from a DisplayPort output to a HDMI input. It will not work the other way around as you are trying to do.
If your monitor also has a DVI input, can you purchase separately an inexpensive HDMI to DVI cable like this -> http://amazon.com/dp/B014I8UQJY to connect your monitor to the dock.
If that does not help, please let us know the brand and specific model numbers of both monitors you are connecting to the dock so we can lookup their specifications online and determine what other connection options may be suitable.
I have also written about video connection options for our UD-3900 dock in detail here -> https://plugable.com/2015/07/06/video… that may help provide additional context.