count is not checking the records in databse. and inserted all the time.

notSystem.Data.SqlClient.SqlException: The Count function requires 1 argument(s). at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection) at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj) at System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj) at System.Data.SqlClient.SqlDataReader.ConsumeMetaData() at System.Data.SqlClient.SqlDataReader.get_MetaData() at System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds, RunBehavior runBehavior, String resetOptionsString) at System.Data.SqlClient.SqlCommand.RunExecuteReaderTds(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean async) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method, DbAsyncResult result) at System.Data.SqlClient.SqlCommand.RunExecuteReader(CommandBehavior cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String method) at System.Data.SqlClient.SqlCommand.ExecuteScalar() at Default2.Button1_Click(Object sender, EventArgs e)

try
        {
            //int count = -1;
            MAconn = new SqlConnection();
            MAconn.ConnectionString = sConnectionString;
            MAconn.Open();
            //string a = "islamabad pakistan";
            MAcmd = MAconn.CreateCommand();
            
            MAcmd.CommandText = "SELECT Count(UserId,GroupID) FROM roles Select UserId,GroupID from Users,Groups WHERE username = '" + TextBox1 + "' AND name = '" + TextBox2.Text + "'";
            int count =(int)MAcmd.ExecuteScalar();
            if(count==1)
            {
                Label1.Text="record exits";
            }
            else
            {
            MAcmd.CommandText = "INSERT INTO ROLES (UserId,GroupId) SELECT UserId,GroupId FROM Users, Groups WHERE username= '" + TextBox1.Text + "' AND name='" + TextBox2.Text + "'";

            MAcmd.ExecuteNonQuery();
            //MessageBox.Show("Inserted Sucessfully");
            Label1.Text = "inserted";
            }
            MAconn.Close();
        }
        catch (Exception ex)
        {
            Label1.Text = "not" + ex;
        }