Means of transport & not specified

What causes this issue?

No <DS:DE.VHART>shipping material type</> has been assigned to the
specified <DS:DE.TRMTYP>means of transport</>.

System Response

The means of transport entered cannot be used.

How to fix this error?

Assign the means of transport to the shipping material type. Also enter
a <DS:DE.VELTP>shipping unit category</> relevant for the shipment.

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.