SAP S/4 HANA 1511 - Issue in linking Plant to Vendor Business Partner in BP

[SanjoyRC]

We are using transaction BP in SAP On Premise edition 1511.  When trying to link a Plant to the Vendor in BP transaction ( using BP Role FLVN01 ), we find that the Plant field in " Additional Purchasing Data " is greyed out :

On clicking on the "Create" button, we are getting a screen where we can enter the Plant, but getting an Error saying Vendor Sub Range is mandatory. We do not need VSR, we only need to assign a Plant to the Vendor BP in order to enable Stock Transfer Order scenario.

Getting the Message " Enter Vendor Sub-Range " as shown above.  So, we are unable to assign the Plant in Additional Purchasing Data.

Any help would be appreciated.