Timeline Link Data to Shapes - ignores date from Excel

[michigandrea]

I am trying to create a timeline from linked data in an Excel spreadsheet.  The data is very simple - four columns with an ID, Task Name, Date, and Start time. I am following the instructions here http://www.k-state.edu/today/announcement.php?id=1460 but I can't get the date to come over from Excel - it inserts 12/30/1899 and I have to manually change it to the date I'd like.

I have a feeling this process is not as easy as it seems at first glance, but I am not sure what else to try, or where else to look for additional guidance.

Thanks!