resolution issues on the DVI port, but not the HDMI port
 

I've got a macbook air hooked up to a displaylink docking station. There are two samsung S22C450 displays connected to that displaylink docking station - one through the DVI port and one through the HDMI with a DVI-->HDMI adaptor. The resolution on the monitor connected through the HDMI port is just fine, but the resolution on the monitor connected via the DVI is off, and only shows the following options: 1600x1200, 1280x1024, and 1024x768...along with the scaled option. I tried switching the cables to see if it was a display issue, but whichever display was plugged into the DVI port has the resolution issue.

Any ideas?