Thanks for the help, everyone!
I bought, some of those fasteners as on the Chris' picture. At first I was breaking them, and making the wall look terrible. Then I started to predrill the wall, before screwing the plastic parts in; that worked like a charm. Weird ? the instructions, did not say anything about drilling, nether did Chris. Perhaps, I wrongly identified the wall type ? it is made out of white stuff (gypsum?)
Anyways. With predrilled holes, those suckers hold things in nicely. I am done practicing on TP dispensers and towel racks, I'll be hanging a mirror next.
