Part of the problem was that I wasn't sending the filename to the next page with an actual $_POST in my form. So the script that was expecting to get the filename was getting nothing.
The other part of the problem was the Absolute Path issue, that you were so helpful with.
The file is being located just fine and is included in the message.
I do have one last issue that I didn't notice until after I made my last post to this thread.
The attachment file is a PDF file. The attachment isn't being treated as an attachment. It's more like part of the message body. I can extract it from the message and save it to my desktop and it's fine, but if I try to look at it in Outlook there is a bunch of code being dumped into the message body.
Outlook doesn't see the attachment as being an attachment. There is no paperclip icon being displayed either. This is true as well in my gmail account. No paperclip icons in either email client.