Wallpapering!

[Ant]

Wallpapering with thick heavyweight vinyl, yet after it has dried small bubbles have developed, why is this? could it be the paste?

[mac309]

Probably that you've not brushed out all the trapped air and now the paper has dried the bubbles have appeared.

[Stewart]

Most likely cause is not allowing the paste to soak into the paper. For a heavy vinyl this could require as much as 5 minutes - check the label. Other less likely but possible causes are poor wall preparation (eg non-porous surface such as oil based paint), using paste on ready pasted product, and as mac309 says, not brushing out all the air. If you can provide any more info I can narrow it down a bit. First rule - RTFL. (Read The Flippin' Label or similar)