Dell D3100 Dock not outputting via HDMI

[MarkP]

Hi - installed this on a Dell XPS 13 recently. Tried the drivers that came on the CD with the box and also downloaded the latest reference drivers. Before the reference drivers were installed we couldn't get any video output from any of the ports. After uninstalling the supplied drivers and installing the reference drivers the DP port started to work and the laptop can now display to two monitors if one is connected to the laptop directly and the other to the DP port of the D3100. However neither HDMI port will display on either monitor. I'm pretty certain this should just "work" as there doesn't actually seem to be anything to configure. We have tried multiple monitors and multiple cables. The cables are HDMI - DP as the monitors have no HDMI inputs. Is anyone able to confirm whether or not this is likely to be a hardware fault with the D3100?

[faeterov]

Wich VGA do you have?