[tendaimare]

I am usiing the code below to calculate the sum of rows in my datatable with the productcode in the textbox but if the code is not in the datatable I get the error "conversion from dbnull to sting is not valid". How can i trap this error in this scenario.

      Try

            RadTextBox8.Text = myTable.Compute("SUM(PercentageInMix)", "ProductCode = '" & txtProductCode.Text & "' ")
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

[tendaimare]

I even tried this

RadTextBox8.Text = myTable.Compute("SUM(PercentageInMix)", String.IsNullOrEmpty("ProductCode = '" & txtProductCode.Text & "'    "))