C220 W203 door locking/ opening problem

[N Fraser]

I have a 2002 c220 and having problems with the drivers door sometimes it will open sometimes it wont same with locking!! have had a new door lock fitted and also a new door control unit. Can someone please help me out.

 

[television]

Hello and welcome,,one thing that should have been done is to apply some rubber lubricant on the locking rod where it passes through the door, as it can stick. when you try to unlock,,does the button try and move