Historical Report Instance and bursting

I'm wondering if someone could help me to understand how bursting works when applied to a historical instance of a report. I have a crystal report that is bursted based a field in the report (user ID) so they can view their page only. The bursting works fine when you select "view the latest instance", however, once a historical instance is created from the scheduler, it prompts for a user ID and password. If you enter the UID and password at the prompt, it opens the report, but managers aren't going to be asked to enter those credentials.

I have saved the user ID and password at the data source selection, when published and selected "use the user ID and password entered above" but it still asks for the info before it displays the report.

Does a historical instance require different settings for bursting security? As far as i can tell, I've configured everything correctly and selected burst in the schedule manager and in the bursting set up.