When you're doing a chained payment the primary receiver amount should be the full amount of the payment. Then the secondary receiver would be whatever amount they should get.
If you want to push the the entire amount, then instead of setting the primary amount to 0, set them both to the same thing.
I'm only mostly sure that will work for you. You'll need to give it a shot and see, but if I remember correctly that's how chained payments works with the amounts.