Using HDMI connection and does not work

I have 2 Asus LED monitors hooked up to the docking station…one with DVI connector-which it works, and the other monitor with the HDMI connector-this one does not work… I can expand to the 2nd and 3rd monitor, but the 3rd monitor is just black…any sugguestion?
Running windows 8.1 and UD-3900 and 2 Asus VE247H 24-Inch Full-HD LED Backlight LCD Monitor with Integrated Speakers

Hi Sandy,

Thanks for getting in contact with us. I’d be more than happy to help you with your Plugable UD-3900. In order to better assist you, I’ll need a bit of additional information.

Could you please provide the logs produced by our tool Plugdebug, you can find it here and then send them to me at support@plugable.com.

http://plugable.com/support/plugdebug

Once we have those logs, we’ll start trying to figure out what exactly is going on with your setup.

Regards,

Stephen
Plugable Technologies