Trouble with Grouping by Year/Month in Pivot Table

I created a pivot table based off data being retrieved from a SQL Server query in March and grouped the results by Year/Month so it showed Jan, Feb, March for 2010. When I refreshed it today, for 2010 it shows Jan, Feb, March, and >3/27/2010.

Why didn't it group the >3/27/2010 data into March and April separately?

Thanks for any help.