Computer wont start after PSU upgrade

[ST34LTH]

Hey i got my psu today and i fitted it in, this is the first time ive done it now for some reason the computer wont start up, the blue light (which means powered on) turns on but the rest of the computer doesnt, no fans no hdd no nothing, im sure ive messed something up with the power supply connections, any ideas on what i can do to get it sorted?

btw this is the PSU i bought
http://www.overclockers.co.uk/showproduct.php?prodid=CA-014-CS&groupid=701&catid=123&subcat=1084

and i have a Foxconn Sanfransisco 2 MoBo

 

[ST34LTH]

Thanks for your fast reply m8,

I put the old one in and everything is fine so im gonna have another go, this time ill put in what i take out, meanin ill take out the old one while installing the new one at the same time, hopefully this will help me remember where everything goes.

again Thank you