Resource assignment to variant &1 does not exist

What causes this issue?

In iPPE, no valid line resources can be determined for the component
&V1&.

System Response

This component is not transferred to the planning matrix.

How to fix this error?

Check:
Is the component assigned to an activity?
Is the activity assigned to a station or a line segment using a valid
line balance link?
Is the line balancing valid?

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.