Trying to authenication userID and Password

I am try to authenication userID and password, I check the spelling of both userID and password.  The problem is it is always false and I know I typed in the correct data.  How am I doing wrong???  Here is my code:

private bool VerifyPasswords(string suppliedUserName, string suppliedPassword)
    {
        bool passwordMatch = false;

        string connection = WebConfigurationManager.AppSettings["ConnectionString"];
        SqlConnection cn = new SqlConnection(connection);
        SqlCommand cmd = new SqlCommand("LookupUser", cn);
        cmd.CommandType = CommandType.StoredProcedure;

        SqlParameter sqlParam = cmd.Parameters.Add("@username", SqlDbType.NVarChar, 5 ...