My only advice would be to be sure you are using the proper kind of candle as was spoken to above.

On other suggestion I might make. As you boyfriend if he would accept having any new toy or technique tried out on himself before he uses it on you. Personally, before I use anything different or new I tend to try it out on myself first (the stun gun was an interesting test). It gives me a good perspective on what my sub is feeling and what I can expect from her and from the toy.