The Sixth Commandment of Selling

"Don't stop til you get to the top"

Never give up on a sale until the top decision maker in the customer's company says no.  And when the customer gives you a seemingly insurmountable obstacle to getting the order, don't stop until the decision maker in your company says no.

In my experience, sales people give up on the sale too easily.  Don't give up.  Keep going until everyone who matters has said "no".