Confirm button Not quite there yet

[Logger]

Help, I’m trying to implement a confirm button on an asp.net page. I got
some useful help earlier but it’s not quite working yet. I have searched the
newsgroups for past questions/answers but I don’t see a clear answer on how
to do this. I’m using the code below. With button1, the confirm
CreateConfirmBox seem to only run if you click button1 twice, which is not
good. I need to close and exit if true, stay and update record if false.

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click
CreateConfirmBox(Button1, "Do you want to exit without saving?")
End Sub
Public Shared Sub CreateConfirmBox(ByRef btn As WebControls.Button, _
ByVal strMessage As String)
btn.Attributes.Add("onclick", "return confirm('" & strMessage & "');")

End Sub

Any help will be appreciated,
Logger