Computer Fails to Power On after putting it together

[compbuilder]

I just bought an ABIT motherboard and installed it into a new case. I transfered all of my peripherals from my old case to my new one. I then tried to turn the power on, but nothing would happen. I had checked long ago to see if all the parts were compatible, and they were. Also, the green power light on the motherboard is on when I connect the power cord to the computer, so I don't know why the system wont turn on. Can somebody please tell me what could be wrong?

 

[Son of Sam]

did you hook the front pannel up?

 

[compbuilder]

Yes, I checked several times to verify that all the wires were properly connected. I just recently tried to turn it on, but it will power up for about half a second and then just shut off.