I'd start by isolating the 35~ cases which aren't included but should be.
Once you've done that, create a new formula as follows and drag it into the dataset - this should give us some idea of what's causing the problem.
today - {table.datefield}
Once we know why they're being incorrectly excluded we can begin to help you fix it.
Regards,
Ryan.
Basically, let us know what the dates are on those 35~ records. I'm guessing your field is datetime not date datatype from it's description so I'm thinking it's probably something like you want <= currentdate -7 at 00:00:00.
Try;
{HPD_HelpDesk.Modified_Time} <= dateadd("d",datediff("d", #01/01/1901#, currentdate())-7,#01/01/1901#)
Edited by rkrowland - 17 Feb 2012 at 5:55am