Never end a sales call without having agreed with your customer on something, even if its not the close of a sale. The objective of coming to an agreement, no matter how small it might be, is to demonstrate to the customer that youre able to move the sale forward.
If possible, gain agreement on one particular aspect of the sale and use this as a building block for the next time you meet. However, if you cant see eye to eye on a particular aspect, you may at least be able to concur on the items you intend to follow up on or a time to get together again. The important thing is that you agree on something and use whatever it is as a next step toward a future sales call.