Canon 500d external flash problems?

I have a 500d and some studio lights, i've pluged them into the external sync that goes on top of your camer but it will not firethe flash. It will of my old nikon camera,
also i have a normal external flash that goes on the top of my camera that works fine. It just will not work on the stidio flashs wen i'm using the sync.jessops recon that it should woerk and ther is no diff between the diffrent makes for the syncs?/

You may have to call Canon for an answer.

Are you saying that you have a hot shoe to PC flash adapter for your Canon?

Some battery grips have PC ports on them. Does the Canon Battery Grip BG-E5 have such a port?

I'm surprised that you switched from Nikon to Canon when most of my colleagues over the past four years have been moving from Canon to Nikon (due to the high ISO with low noise found on the D3 and D3s cameras)

The PC socket could be bad, the cable could be bad, or the adapter is not seated properly in the hot shoe. I'd start with the cable, then just replace the adapter if the cable is good. If you can drag it all to Jessop's, they may be able to help you troubleshoot the system as a whole, which is much easier than trying to do it one piece at a time.