Question: I have a checkbox column in gridview and getting its Click event. But I just has relised I do not need Click event rather I need to know the events if checkbox is checked or unchecked on Client side. But these events are not available.

Please guide how to handle this.

Answer: 
This is the VB.Net version as if you would use it in an vb.net-exe. It will not work in EXCEL.VBA, but as I understand it you wanted a VB.Net version?

```
Imports Microsoft.Office.Interop

Sub ChangePivotTableSourceData()
    Dim e As New Excel.Application
    e.Workbooks.Open("c:\testdoc.xlsx", , True) 'Open the doc readonly
    Dim sheet As Excel.Worksheet = e.ActiveSheet

    For Each table As Excel.PivotTable In sheet.PivotTables
        table.SourceData = "'" + Split(table.SourceData, "]")(1)
    Next

    e.ActiveWorkbook.SaveAs("c:\testdoc_changed.xlsx") 'Save under another name
    e.ActiveWorkbook.Close()
    e.Quit()
    sheet = Nothing
    e = Nothing
End Sub

```
Interop sucks basically. Check your processes (task manager) ... there should be at least one excel.exe process that isn't visible on the desktop. Kill them since they might have the file in use. That causes your 'Can not open the source file C:\file.xlsx' error. And who knows it might also fix your other error.

If it doesn't, check if you installed the latest interop assemblies and use those. It helps when you're dealing with Office products.
<http://msdn.microsoft.com/en-us/library/15s06t57(v=VS.100).aspx>