Query stops working with ODBC to SQL Server. Help!

One of my queries which was working fine in JET, stopped returning any
values when I connected my Access 2003 Database to a MS SQL Server
2005 backend. This is for the part of myh applciation that generates
an appointment calendar. I have two recordsets:

1) ApptFltr, which is generated by a Access query which filters one
days appointments for one staff member.
2) TimeSlots, which lists all the available appointment times

The query stretches the appointment out so that it "fills" the
calendar.

SELECT ApptFltr.Date, TimeSlots.Slot, ApptFltr.StartTime, ApptFltr.ID,
ApptFltr.Duration, ApptFltr.[Appointment Type], ApptFltr.[Appointment
Status]
FROM ApptFltr, TimeSlots
WHERE (((TimeSlots.Slot)>=[StartTime] And (TimeSlots.Slot)<[StartTime]+
[Duration]-#12:01:00 AM#))
ORDER BY TimeSlots.Slot;

With a ApptFltr.Duration of 8 hours, for example, it fills 16 1/2
hours timeslots.

.