no suitable method found to override

Hi,
 
I am trying to create my own membership system. Therefore I created my own membershipuser class and membership provider class. But I am getting the following error on Createuser method of My membership provider class;
no suitable method found to override 
This is how my CreateUser method looks like:
public override MyMembershipUser CreateUser(string username, string password, string email, string status, int registerd_on, out UserCreationStatus creation_status)
{
//code...
}
 
 
 
...