I cannot seem to get the email message with my invoice reminder to stick.  I'm pretty sure I've followed all the instructions and everything looks OK in Account and Setting -> Sales -> Reminders as well as in Customer form styles -> Emails but instead of the actual, correct message showing in the email it just appears as the text "Email message."

I've done plenty of these in the past without any problems (although not for some time) so I don't know why this issue is appearing now.