Grouping dates in pivot table

I am pulling data from a SQL Server database to create a pivot table.
Excel (07) is not recognizing the field as a date. This is a field I
would like to group by in the pivottable. I am aware of all the
techniques to convert this to a date field, but I am searching for an
answer as to why XL pivot tables cannot consume the dates directly
from a sql query.

I have played with bringing the dates back in a number of differenent
formats with no success.

Any insights into this would be appreciated.