Cannot achieve max resolution

[dka]

I have installed an iogear external usb dvi video card and have connected it to a samsung syncmaster 2233 which is supposed to have a max resolution of 1920 x1080. The dvi video card is supposed to have the same max resolution. However, I am unable to set the resolution higher than 1440 x 900. When I attempt to set a higher resolution, the monitor displays just a black screen. I have installed the latest version of the displaylink software. Any ideas?

Thank you.

dka