Membership.CreateUser Question

Question

C# security Question
Hi I'm wanting to be able to create a user in the aspnetdb membership table with just a username, tmp password, and their email (these are known people), send an email to them and a link to have them fill out the security question and insert/update/change their password, and I seem to be having problems with that. I'm trying to use the Membership.CreateUser control but, I it's not working for me.. can you help?  suggestions? links? examples?