If you format a column of dates in your pivot table source data, to show as year and month (yyyy-mm), they won’t automatically summarize by year and month in the pivot table. Format the Source Data For example, in the source data shown below, there are several orders for January 2010, and three different dates [...]

In Excel 2007, you added a date field to the pivot table’s Row area, and you want to group the dates by year. However, you get an error message, “Cannot group that selection”, when you try to group the dates. This error occurs if there are cells in the source data that contain text, instead [...]