I need to sum the data from a DataGrid colum (W) into a textbox below the Datagrid (textbox3.text = SUM([W]) ).
For this I have tried to use:
But it generate the erorr: "An error occurred creating the form. See Exception.InnerException for details. The error is: Conversion from type 'DBNull' to type 'String' is not valid."Code:Me.TextBox3.Text = VBTestDataSet.Invoices.Compute("sum(W)", String.Empty)
I don't know what to do...