I think you're using a splitter. So it will just split the images between the 2 screens. It says you have an HDMI port. Do you have one that looks like this (it's the white thing).
Which OS are you using? Modern cards will rely on the modern OS to handle that and your radio shack hard splitter is the problem.. get rid of that.. that's all I'll say..
get rid of it.. it's archaic and confusing your card in relation to your modern OS.. it's obvious.