Configure Shortcut Attachments for POApvMsg

I would like to use a shortcut attachment in my bpm generated e-mails for purchase order approvals. I’m following the instructions for this that were in one of the Advanced BPM extended education class at Insights.

I’ve got my e-mail working properly without the shortcut, but am stuck on setting up the Alert Attachment because the POApvMsg table is not listed in my list of tables to select from in Alert Attachments.

Any thoughts on this?