You have not entered a reference object in the maintenance item

What causes this issue?

You have not yet entered a reference object in the
<DS:GLOS.3526C331AFAB52B9E10000009B38F974>maintenance item</>.

System Response

If you do not enter a reference object, the system cannot determine any
default values for the planning data of the maintenance item from the
reference object.

How to fix this error?

If you want to create a maintenance item with a reference object, enter
the reference object in the maintenance item. Only then can you be
guaranteed that the planning data for the maintenance item will be
proposed from the reference object.

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.