Problem whit replacing screen.

Hakebar

Hi,

Maybe somebody here can help me whit my problem.
I changed the screen of my Umi and when I test it without the backcover the lcd and digitizer works fine.
When I click the backcover on, the lcd works but the digitizer not.
When I remove the backcover, everything works fine again.
I can't see no pressure problems.
What do I mis?

Thanks for a reply.