hello all... 1st post, so go easy on me!

I have just bought a new exterior door handle for my 55 plate Audi A4 as the other one had scratches on it from the previous owners ring.

I have had it sprayed up and am now trying to refit it. I can see a sliding latch that looks like it needs to be slid to one side once the bottom catches of the door handle are lined up, but I can't for the life of me get it to slide accross!

Just wondering if there is a trick to it!

Thanks in advance