Curious, who dx'd you with an over-active bladder? Urologist or your family doc? What test(s), if any were done or were you given this dx based on symptoms alone?
Generally if a person truly has an overactive bladder and medication that is designed just for that purpose and does not work, then something else is going on.
If I woke up in your shoes, I would find a good urologist and get to the bottom of the problem.
~Zig