Usually, the problem is the perforation isn't deep enough. In other words, the Paper Tiger isn't scoring the paper enough.
The DIF works fine on ALL types of paper. Well, it really doesn't do anything to the paper; It 'works' on the glue. To get to the glue, you MUST score through the paper, and you need to score it a great deal. It's tough on your elbow and arms. Only score the paper deep enough to 'break/tear' the paper. If you PUSH too hard, you'll end up with a HUGE spackeling job.
The other advice I have is to re-read the directions. I know, I know, you've done it. BUT, you have to do exactly as it says. BOILING, HOT water! Use gloves and a car sponge (like those big, bulky ones.) Lay plastic and newspaper on the floor to prevent a big mess. AND, you do need to wait 15 minutes between 'coatings'. You coat, wait, coat again, wait, coat a 3rd time (that's a step I added) and IMMEDIATELY start 'scraping/peeling'. I like the 3rd coating because I want the wall to be WET when I work on it. When the DIF mixture gets cold, you need to CHANGE it; not 'beef it up'. Change it ...
You may be doing 99% of what I'm saying BUT if you don't do just 1 of these 'things', you job will go bad. Oh, If the wallpaper is vinyl or 'plastic feeling', it's REALLY important to make sure you get a lot of perforations. Again, the perfs need to go THOROUGH the paper. (The DIF works on the glue; not the paper.)
My best to ya and hope this helps.
Jay J -Moderator
PS: If you need more 'guidance', e-mail me directly and give me more 'facts' ...