Have you double checked the role of the templates? It might be that you're setting the Detail role to the wrong template, and should have an Append instead of a Footer. Hard to tell without a sample report. From what you say, it might be that you're trap characters for the two templates are the same, or that there's a multi-line template going on here, like an upside-down 'guru trap'. If you email the report and model over, I'd be happy to have a look.
I would love to send the report to you. However, for confidentially reasons I am not allowed to provide it
If I get some free time today, I will try to mock up my own dummy report.
I am trapping my detail information, and the next set of information I want can be on the same line as the detail, it can be many lines before the detail, or it can be many lines after the detail. I was capturing the information with the detail line. I then created an append to get any information that happened before the detail line, and off of that I am doing a calculated field. If the detail line is blank I take the information from the append. Everything is good up to this point. Then I add the footer in, and a line of data disappears and it seems to be doing that because there is no footer for the last record to pull.