Select exactly one shipment stage OR one point

What causes this issue?

In the graphic, you have either selected no shipment stages or more
than one shipment stage OR you have done this for shipment points.
However, only one stage and/or point can be selected.

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?

Use the mouse to select the shipment stage or point from the network
diplayed, for which you want to display details and call the desired
function.

Error message extract from SAP system. Copyright SAP SE.