Local SQL problem.

I am using Delphi 1.0 under Windows 95.
And the following SQL-statement just causes my computer
to hang, or causes a GPF:

-------------------------------------------
SELECT
  Customer.Name
  Invoice.Number
FROM "Cust.DB" Customer, "Invoice.DB" Invoice
WHERE
  (Customer.Number=Invoice.Customer)
  AND
  ((Invoice.Date+Invoice.NumberOfDaysUntilDue) >= '07/07/96')
--------------------------------------------

But the two following SQL-statements work perfectly:

-------------------------------------------
SELECT
  Customer.Name
  Invoice.Number
FROM "Cust.DB" Customer, "Invoice.DB" Invoice
WHERE
  (Customer.Number=Invoice.Customer)
--------------------------------------------
and
-------------------------------------------
SELECT
  Invoice.Number
FROM "Invoice.DB" Invoice
WHERE
  ((Invoice.Date+Invoice.NumberOfDaysUntilDue) >= '07/07/96')
--------------------------------------------

Have I done something wrong?

Or is this yet another limitation in Local SQL, just not
with the "Capability not Supported"-message.

Regards,
Hallgrim Ludvigsen