I have a Cannon t3i and I'm having problems syncing my square perfect lighting studio. I have followed the directions in the instruction booklet for wireless flash sync, but have had no luck. Sometimes the lights fire too soon, sometimes too late. Is there a way to sync the lights using a wire? There is a PC input on the slave lights, but I'm new to photography so I don't know what they are used for, or if there is an adapter that would hook the lights up to my camera.