Error page not displaying all the time

[tshad]

I have an error page that I go to from my Sub Application_Error event that
is in my Global.asax file.

This works most of the time. The function sends me an email on what the
error is.

But in some cases the user still gets the error page. I just had a user
call me saying they got the ugly detailed error page. My Application_Error
function should have prevented that.

I have my web.info entry for custom errors set to:

<customErrors mode="Off" />

If I change it to On, I get the page that says I should change my web.config
file. Putting in the defaultredirect attribute doesn't work either.

This is the error page where it can't find a module.
***********************************************
Compiler Error Message: BC30002: Type 'CBillingModule' is not defined.

Source Error:

Line 1018: Sub ChargeCard()
Line 1019: Dim strErrors as String
Line 1020: Dim objBillingModule As New CBillingModule()
Line 1021: If objBillingModule.AuthorizeCard("sta: " & "Intz", "(e-mail address removed)",
_
Line 1022: "120 Bison Ste ", "92610", 1, "", "12" + "06", "25") Then

Source File: C:\Inetpub\wwwroot\stp\employer\secure\job.aspx Line: 1020
****************************************************************************************
Why does it not work on this error and on other errors it works fine. In
this case, the Application_Error function is called. But the last line in
the function is:

response.Redirect("/PageError.aspx")

This doesn't seem to be happening.

Why is that? What point is there in having an error handler when it only
works some of the time?

Thanks,

Tom