Asus M4A785TD-V Evo Problems

[Miller220]

Hey guys, new to the boards, and PC building in general. My first build over the course of today...went moderately well....untill funny enough I came to something I knew...and which are easy....the graphics card. I've got everything new, with the exception of my gfx card, which is an 8400GS..till I can save to get a 4890 or something. ANYWAYS, my issue is my mobo refuses to see the 8400. Any ideas why? I updated all my bios...so..... I dont know what to do. Everything is running the way it was configured when I pulled it out of the box. Thanks for any help

If it helps...here's my PC

Mobo: M4A785TD-V EVO
Proc: PII x3 720 BE
Ram: 2x1 Gig g.skill
HDD: Western Digital Caviar 500Gig
PSU: Antec 650W power supply
GPU: (for the time being) 8400 GS