How to fix the side mirror?

[Dynamix]

Hello guys,

I have another tiny problem with my Alero. During the head gasket thing, I had to remove the passenger side mirror. After fixing the engine, I wanted to put the mirror back to his place, but now the mirror wont hold anymore. Is there any trick on that or did I destroy something that should hold the mirror? There seems to be no hook or similar to hold the mirror. The rubber string is still on the place where it should be!