ranged datetime query problem

[Sean Wilson]

>Here's my SQL query:
>SELECT SUM(time_spent) FROM tblTimes
>WHERE
>(start_time BETWEEN '1/5/2006 0:00:00:000' AND '31/5/2006 0:00:00:000')
>AND
>(stop_time BETWEEN '1/5/2006 0:00:00:000' AND '31/5/2006 0:00:00:000')
>AND
>(job_name_ptr->job_name = 'Job Name');

A little more probing suggests it's my use of the -> operator that's 
failing me and not necessarily date ranges. I need to do some more 
poking around before I can be categorical about where my problem 
comes from, though if anyone can spot anything obvious...

Even replacing the following clause:
(job_name_ptr->job_name = 'Job Name')
with
(job_name_ptr = (SELECT recID from tblJobs WHERE job_name = 'Job Name'))
yields a SUM() on an unrelated job name.
So it seems I'm grabbing time_spent related to the wrong or incorrect 
job_name. Maybe I set up my objectPtr incorrectly, or I could be 
using the link table to simplify the SQL query.
It doesn't matter what job_name I feed the above clauses, I get 
nothing back unless I use the job_name whose recID = 1 *even though* 
there are /no/ related records in tblTimes

I'm thoroughly confused now. Database and queries (~8 KB zipped) are 
available if anyone is interested.

Thanks,
-Sean.