Don't know what I'm doing wrong in my Unit Test

I have a Unit Test for my LoginSystem, and it's failing and I have no idea why, In my opinion I think my code is correct, it seemed to be working for the past couple of weeks and I only found this error through Unit Testing.

public bool matchCheck(string Username, string Password)
        {
            //create a new bool and set it to false.
            bool returnvar = false;

            //for each basemember in the list of members.
            foreach (BaseMember bm in hillracing.Members)
            {
                //if the username is equal to a list item username AND the password is also equal.
                if (Username == bm.userName && Password == bm.passWord)
                {
                    //they exist within the same object, so return true.
                    returnvar = true;
                }
                else
                {
                    throw new Exception(" Did not match!");
                }
            }

            //return this bool, true or false.
            return returnvar;
        }

Can someone tell me why my exception is always thrown? thanks.