combobox to 'show all' when checkbox is true

[honeydew]

I have this code in place where a combobox will show 'Codes' where codes = 'Y' and status = 'A' from a database. There is a checkbox that says 'show all' and when it is checked, it should show all codes where the status = 'A' and not matter if the code is 'Y'. (some codes = 'N') But it is not working. Can anyone see why it is not working? This is the only code i have in place for this checkbox.

                if (Combobox.Checked == true)
                {
                    Datatable= Main.SQLQuery_ReturnDS("Select Code Display, 2 from Code_Support where Status = 'A' Union All Select '', 1 ORDER BY Code").Tables[0];
                    DataColumn[] CodekeyColumn = new DataColumn[1];
                    CodekeyColumn[0] = Datatable.Columns[0];
                    Code.DataSource = Datatable;
                    Code.DisplayMember = "Display";
                    Code.ValueMember = "Display";
                }
                else
                {
                    Datatable= Main.SQLQuery_ReturnDS("Select Code Display, 2 from Code_Support where Code = 'Y' and Status = 'A' Union All Select '', 1 ORDER BY DOSCode").Tables[0];
                    DataColumn[] CodekeyColumn = new DataColumn[1];
                   CodekeyColumn[0] = Datatable.Columns[0];
                    Code.DataSource = Datatable;
                    Code.DisplayMember = "Display";
                    Code.ValueMember = "Display";

                }

[Arjay]

How does this code get called?