String usern = CreateUserWizard1.UserName;
MembershipUser usr = member.GetUser("usern",false);
The line is looking for a "hard coded" user name "usern" which I think you meant for it to use the line above, without the quotes (")
Making it:
String usern = CreateUserWizard1.UserName;
MembershipUser usr = member.GetUser(usern,false);
I would personally add a check around usr before dealing with it, something like
MembershipUser usr = member.GetUser(usern,false);
if(usr != null)
{
usr.IsApproved = true;
Membership.UpdateUser(usr);
}
else
{
}
-DB