Upload interim entries: Maintain one table only

What causes this issue?

When uploading meter reading results using BAdI BAPI_MTRREADDOC_UPLOAD
or the IDoc of category ISU_MR_UPLOAD02, <ZH>one table only</> must be
filled in the BAdI interface:
Table METERREADINGRESULTS is for the meter reading results to be entered
Table METERREADINGRESULTS is for the meter reading results to be changed
Table METERREADINGRESULTS is for the meter reading results to be updated
Either you have not filled any of the tables or you have filled more
than one table.

System Response

The system issues an error and terminates the upload process.
The meter reading results are not imported.

How to fix this error?

Enter data in <ZH>one table only</>.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.