Double glazed front door?

could be one of two things,

If the door is new, the holes behind the espagniolette where the mechanism is may not be routed properly, remove the mechanism from the side of the door, this will require removing the handle and lock, check to see if the metal slides freely, if it does, just cut the plastic back with a chisel or drill out the excess plastic (do not be to heavy handed whilst doing this, take your time and dont remove more than is needed) If it doesnt move, you may need a whole new mechanism.

carl
August 2010