I just answered in the other thread - but much better to have a new thread for this and hopefully we can help you work the problem. I'm sorry I didn't see this thread before now, not sure why?
Generally polymer clay will not stick to smooth surfaces like glass and metal, so you need to glue in place after or wrap it around in such a way that the clay naturally holds itself mechanically in place.
Doing the latter can risk expansion cracking though.
I have had some sucess smearing a little PVA white glue onto the bottle or tin can before applying the clay sheet - you need to allow the glue to dry until it is just still tacky - not dry, but not completely wet either.
That seems to bake up quite well and hold the clay in place. If you can scratch up the smooth surface of the item your applying to, all the better. So with cans, just scratch the surface a little with coarse sandpaper and then wipe clean. That gives the clay and/or clay&glue something to hold on to
When baking on glass or metal - i put the item into the oven cold and heat slowly to temp, then baking the lowest temp/time needed and shut the oven off leaving the item inside to cool slowly
This minimises expansion/contraction cracking