well, it can only be one of two things, empty gas bottle, or the ignitation switch
had actually checked the most obvious things and some not so obvious have you used this type of smoker?
oh yes, its a blowtorch basically, so either empty gas, blocked gas pipe, or ignition, cant see anything else that could stop it
they are great for doing under buildings especially with concrete floors ,chainsaw better on the bigger rat earths take both if possible