You cannot enter the sample size manually for inspection type &1

What causes this issue?

For inspection type &v1&, settings are made for an inspection with a
task list, material specification, configuration or batch
determination. However, the sample size is to be entered manually. This
combination is not allowed.

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?

Either cancel the "Manual sample" indicator, or the "Inspect with
material specification", "Inspect with task list", "Inspect by
configuration", "Inspect by batch" indicators.

Error message extract from SAP system. Copyright SAP SE.