If you have an older batch it will burn due to the increased BA alchohol content, although it is painfull as hell its safe to use. If you do a search for "cook and testanon" or something like that you should come up with a few threads on how to heat off the extra BA alch. without altering the compound, which will solve the problem. Otherwise here are some tips that help:
Mix it with deca or eq or some other AS.
Inject Slowly and after injection take a hot rag and deeply massage or rub it in a circle motion to 'spread out' the juice underneath the skin.
Take a hot bath or shower after the injection.
Warm the testanon before injection.
The new batches are not nearly as bad, but until all te old ones are off the market some may still have problems until all the old ones are gone.