When you ran the install, what options did you choose?
If you create a user called admin, after the fact, that user won't be an admin until they are added to the administrators role in the database.
One fix, if you have adatabase access, would be to replace the password/password salt values in the asp.net membership tables in the DB for the HOST user so you can login as a super user. Replace them with the values of the user you created so you can know what the password is