DS Lite keeps resetting

Hello,

I just put a new screen in my DS Lite. I did it very gently, but after I put it back together it starten having a problem. When I power it on, it asks for a name, a birthdate, a date and time etcetera.

After all the questions it says it will power off and I have to power it on again. That all is normal when you've put in a new battery. BUT, after I power it on again, I have to answer the questions again.. And it keeps on resetting like that...

What could be the cause of this problem? Is there a way to solve it?

Thanks allready!

Johan