UPVC patio door - handle will not lift up?

When the door is unlocked the handle cannot be raised at all. The only way to raise the handle is to turn the key in the lock as far right (clockwise) as possible. When the key cannot turn any further (and holding it in that position) it is then possible to raise the handle and then to lock the door.

I have tried replacing the lock barrel and the handle, but the problem persists. It seems that the internal mechanism within the door is out of alignment in some way.

Does anyone have any idea what the fault could be, and how I can fix it?

D Perkin
February 2010