Smoking Ice but no smoke!

[frenchywife]

SWIM has smoked meth a couple of times using an oil burner and would always blow out huge plumes of smoke. SWIM decided to take some time off and has decided to hit the pipe once more. However, it seems that something is either majorly wrong or SWIM is an idiot. For some reason, when SWIM and friends now hit the pipe, no smoke comes out - what is going on?

SWIM was always under the impression that the more smoke blown out, the better, is this true? SWIM thinks the procedures taken are correct: fill pipe, light pipe, but gently to melt/vaporize the shards, let cool and then let it recrystallize, then hit it!

Any ideas or suggestions - thanks!