Confirm - pop up window

I have an application where I am trying to get my "confirm" message box to work. The scenario is: User brings up a page showing a crystal report and click the button to save the report to file. If report already exists I need to show a message box to confirm that user wants to replace:   Public Overloads Sub MsgBox_Confirm(ByVal Message As String) 'Confirm
Page.ClientScript.RegisterStartupScript(Me.GetType(), "Confirmation", "Confirmation();", True)
End Sub
 
Protected Sub btnConfirm_Click(ByVal sender As Object, ByVal e As System.EventArgs)
...action code goes here ....
End Sub
 
<script type="text/javascript" language="javascript">
function Confirmation()
{
if(confirm("Daily Sal ...