I have some wallpaper I removed from the bedroom wall. It had been put on over wall liner. The liner came off with the paper on 2 walls and remained on the other 2. The problem is that on these walls I can not get the paste off the wall for the life of me. I have tried EVERYTHING. It's very hard like dried super glue and water/liquid does nothing to it at all. Can I just put more paintable wall liner over it or can I just paint over it? Even sanding hasn't done much good at all. I used 80 grit or whatever and it did nothing. This stuff won't budge. I've had no problem getting the paste off all the other walls in the other rooms. Any advice?