sum of integer values in a lable retrive from database having formate ##,###.00

hi... all
plz help me for this regard...
I have 3 Label and want to sum of two values into third label with follow this formate. tostring("##,###.00;(## ,###.00);-")

Explanation ...... example ..
I featch the data from data base into 2 label. And want to add this value in third label
code...
.......
while (reader.Read())             {
                 lbllab03.Text = Convert.ToDecimal(reader["LAB03"]).ToString("##,###.00;(##,###.00);-").Trim();                 lblmsc03.Text = Convert.ToDecimal(reader["MSC03"]).ToString("##,###.00;(##,###.00);-").Trim();             }< ...