Box2D related compile error

When I try to set up a project with box2d on ios i run into the problem "Duplicate symbol b2ContactFilter::ShouldCollide(b2Fixture**, b2Fixture**)………
I suppose it has something to do with both the cocos2dLib and my project is trying to compile it but Im unable to solve it, any ideas?

Hi, Henrik,
I just test the xcode4 template, it works well in my environment:
* Lion, Mac OS X 10.7
* Xcode 4.1
* cocos2d-1.0.0-x-0.9.0

Could you please tell me your compilation environment?