Ctrl+. doesn't work on implementing MembershipUser

In visual studio 2010 I am trying to create a custom MembershipUser. When I type in:

    class CustomMembershipUser : MembershipUser

And then hit Ctrl+. to try to implement the abstract class MembershipUser, it does not bring up the option to do so. I can do this successfully with the MembershpProvider and RoleProvider classes, but just not with the MembershipUser class.

Any ideas?

thanks.