Upon running the following queries successively in VBDemo, I get an "Optimizer is turned off" error:

INSERT INTO "JournalEntryCreditLine" ("RefNumber", "JournalCreditLineAccountRefListID", "JournalCreditLineAmount", "JournalCreditLineMemo", "FQSaveToCache") VALUES ('1', '800001D1-1187278368', 0.01, 'MRP transaction', 1)
INSERT INTO "JournalEntryDebitLine" ("RefNumber", "JournalDebitLineAccountRefListID", "JournalDebitLineAmount", "JournalDebitLineMemo", "FQSaveToCache") VALUES ('1', '800001CD-1187278037', 0.01, 'MRP Transaction', 0) 

How can I prevent it from occuring.

Thanks!

This normally happens when you have a QODBC v5 registration and are using QODBC v6 or higher. Check the about tab in the QODBC Setup Screen for the current status of your license and your optimizer settings.

The use of the optimizer requires a QODBC CD Key.

My optimizer settings look exactly like your screen shot. And here is how the "About" tab looks like (with the serial number obscured):

If it helps, this problem began after I switched over the QB file to a test file which is an exact replica of the original file.