connection file that is incompatible

[JuicyJuice]

I have Excel pivot tables where the source data are queries in Access. The pivot tables and queries were originally built in 2003, but both have been converted to 2007 files: .xlsx and .accdb
I add new data to the db every month, then I refresh the pivot tables and voila! the new month's data is in the pivot tables! This month, however, circumstances have changed: I click refresh, but nothing happens. I go to change my source data to check the source, but it's listing a blank query. I try to reestablish the connection with my db and get a Microsoft Office Excel error that says, "You cannot choose a connection file that is incompatible with the existing connection."
Huh??? Suggestions?

Thanks!