Vendor Payments open items

Hi Experts,

If I view vendor line item through FL1N, I can see 3 open items. But if use tcode f-53 and try clearing I am able to see only 2 line items instead of 3. I have checked the 3rd one which has no payment block.

How is it possible that the third item is not showing.

How to overcome this issue.

Thanks in advance

Narayanan