AV8 Power Problems

Hey guys I'm having a little problem with my mobo and any help would be greatly appreciated. I just finished assembling my new watercooling rig and im pretty excited however i can power everything up but when i go to start up the pc through the soft on switch it does not turn on. The PSU is fine and the mobo is on with no error post. It just won't turn on through the case power switch. I have a 400w Ultra PSU and a Abit AV8 mobo. I also have a full watercooling system with a couple of 12V pumps a couple of neon lights a hd, and cdrom. Could it possibly be the PSU or is it just a faulty switch? I'm positive its all connected up right including the switch to the mobo...Any help would be great!