NewBie: Problems With DELETE Statement

I am trying to delete records in a table if a flag set in a linked table is set, but seem to be having problems with it. Neither of the following work:

DELETE FROM DSCar WHERE SerialNum IS NOT NULL
AND DSCar.SerialNum=DSOrds.SerialNum
AND DSOrds.StatusFlag='3'

This reports DSOrds.SerialNum could not be bound

DELETE FROM DSCar
INNER JOIN DSOrds ON DSCar.SerialNum=DSOrds.SerialNum
WHERE DSOrds.StatusFlag='3'

This reports Incorrect syntax near the keyword 'INNER'

But a similar SELECT statement works fine:

SELECT * FROM DSCar
INNER JOIN DSOrds ON DSCar.SerialNum=DSOrds.SerialNum
WHERE DSOrds.StatusFlag='3'


I think it is something simple but am having a real head scratcher.

Thanks