You must enter the SI data completely before you enter the DEUEV data

What causes this issue?

You entered DEUEV data although the SI data has not been entered
completely and error-free yet.

System Response

Your entry is rejected because the DEUEV data check is only possible if
the SI data is complete and without errors.

How to fix this error?

First maintain the SI data completely and free of errors.
Then enter the DEUEV data.

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.