Data base index & is to be activated for using the ISR number

What causes this issue?

If the vendor is to be determined using the ISR subscriber number, a
corresponding data base index must be created. That is not the case in
this installation. Although the named index is defined in the SAP System
and has been activated, the index has not been created in the data base.

System Response

You cannot activate the required option.

How to fix this error?

Ask the data base administrator to create the index <ZH>&V1&</> on the
data base for table <ZH>LFA1</>.

Error message extract from SAP system. Copyright SAP SE.