1080p not supported?

I've been trying to figure out how to get my ASUS Radeon hd 6870 to output 1080p on my insignia 32" hdtv. I know the tv supports 1080p because i can use it with my xbox 360 and ps3. I was also able to use 1080p resolution on my laptop with an nvidia geforce 9600m gt. One reason i think could be a problem is that i have to use a DVI-D to HDMI adapter because my tv does not have dvi input and the graphics card only has 2 dvi and 2 dp outputs. Currently i am only able to get 1080i resolution at 30hz, but i want 1080p at 60hz. CCC even says that my tv supports 1920 x 1080 at 75hz but will not give me that option. I have also tried to add the resolution through the HDTV support menu but when i check the box for 1080p at 60hz, it will not give me that option in the display settings.