Replaced Door Lock Mechanism - Now Exterior Door Handle Doesn't Work Correctly

Hi,

I just replaced the drivers side locking mechanism on my 2003 Fabia VRS (microswitch had failed, kept leaving lights on blah blah blah) and now the exterior door handle only opens the door once you have hit the door just above the handle?!?

It then functions correctly to open and close the door as many times you like, until the car is next locked and unlocked again. At which point, I have to hit it once more before the door handle will work.

Have I got something out of alignment somewhere or is the replacement locking mech even more knackered than the old one??