Is it uncommon for botox for hyperhidrosis to not work the first time?

I've had hyperhidrosis since age 13. I finally had botox treatments about three weeks ago, and was sure that this would be my answer. The sweating has improved some, but I still get sweat marks. Which, for the price I had to pay, is incredibly disappointing. I don't know if it's worth it to try again or not. My dermatologist's office said insurance wouldn't even allow me to get another treatment until it had been 4-6 months. They also said nobody had ever had the botox NOT work for them. Help!