Only use indicators "0", "1", "2", and "3" for WM staging

What causes this issue?

The system requires the entry of a material staging indicator.

System Response

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

How to fix this error?

You generally have four material staging indicators to choose from:
"1" for direct picking
"2" for crate parts
"3" for release parts
"0" for no WM picking
Based on other settings, you may not always be able to select from all
four indicators.

Error message extract from SAP system. Copyright SAP SE.