Character falling through Triangle mesh

This happens with some static triangle meshes.
Its pretty random how it happens, sometimes i can walk over and sometimes i cant.
Oh, and i i have CCD activated it on the character capsule.

Here in the picture you can see i can walk on the sides, but not in some parts of the floor.
Its divided on chunks of geometry,that make basic representation of the actual meshes but it doesnt seem to be polygons missing or something.

oh well... the problem was that some polygon faces where inverted, and i was falling throught those...