problem with custom membership provider

Hi,


In my site, I want the administrator to be able to reset password of user without the need to provide the security answer. Therefore, I create a new member provider
In web.config, I add these lines:
"






"
Then the error is "Default Membership Provider could not be found "

I do not know how to know what is my membership provider, where to find its name?
Hope that you'll help me, thank you very much ...