Part of the prob with Ammo-lok is you never know when it is ammonia or just the ammo-lok giving the ammonia reading....
Do you have Nitrites? If so then you probably do have an ammonia problem, if not then maybe the ammonia is taken care of and what is left is a false reading?
Have you made any drastic changes to your tank prior to finding the ammonia problem (added fish, changed water source, added live rock, stirred up the substrate, squeezed a sponge filter, etc..)
What are your tank readings after your water changes (ph
, ammonia, nitrite, nitrate)