Painting - HELP! I see lines!

I am working on restoring my apartment. We are in germany so the walls are all cement based, not dry wall. The walls are brick with cement over it. We compeletly redid all the walls. At the advice of a painter he suggested covering the walls in a support paper that seems like it has fiber glass in it. You put it on like wall paper. We put this up and then painted over it with the recommended primer. However the lines where the paper comes together show through. The painter who suggested it doesn't have a clue as to why. His only guess is there was more glue at the seams and it is absorbing the paint differently. Being that this is primer it should take care of this by sealing, yes? Any suggestions on how to cover this area?

Was the support paper called 'tassoglass'? It sounds to me that when the paper was put up, it was probably supposed to be doublecut at the seams, making the seams invisible. If this wasn't done, then that might be why you can see them. Maybe caulking the seams somehow would make them less noticable.