Will not allow a drop ship order

We are on JDE 8.0. We have a group of parts from the same supplier (same everything) we cannot process a drop ship order on. We get an error message "blanks invalid". We can however process a regular "S" line type. We have been through everything, set up of Item, price, supplier and don't see anything missing or incorrect. Has anyone experienced this? Can you help?

Hi there! I would try two things upfront

1. Try placing a standalone purchase order using the same version of P4310 that you have in the version of P4210 direct ship sales
This would hopefully show the same error and highlight the field that has an invalid blank value

2. Check if you have transportation turned on for D line type but not S line type (UDC 49/SD) If yes, it could be a mistake in 49/SD or the transportation setup is incorrect

Hope this helps
/Aarto