Problem with dates and group by

[sdillard]

I am working on an application in which I link to data from a MS SQL database in order to create an extract of the data on my PC. The data I am pulling down is collected in different time zones so I need to recalculate the date time to make sure they are all in sync. However, after I recalculate the time using the DateAdd function, the group by the date/time field does not work correctly in my query. Rather than group by the half hour (which is how it should based on the times displayed) it groups with two times for each half hour.

Example:

02/21/2002 10:00:00 AM
02/21/2002 10:00:00 AM
02/21/2002 10:30:00 AM
02/21/2002 10:30:00 AM
...

There is nothing in the information displayed that would tell me that the two 10 AM times are different and thus not included in a grouping. What am I missing? Are there additional undisplayed decimals or something?

Any help would be greatly appreciated.

Thanks