The eccrine gland and the other crine gland (forget the name of that one... akocrine or something...) are what controls sweating in the body and hyperactivity in these glands could cause you to sweat more; there's obviously a reason for it, but known yet identified, aside from a theory of it being genetic... If you have health insurance, I'd suggest you a see a doctor; sometimes excessive sweating can be linked to other problems, like thyroid and psychiatric disorders (probably neither being the case), but a more reasonable reason to see a doctor would be for a script for deodorant that WILL work for you.
Also saw on Discovery Health a woman with excessive sweating that couldn't do anything to stop it so she got silicone but into her pits the block off the glands and it stopped the sweating quite successfully... but that would be if you really really come into bad sweating issues. o.o