When I run your model I get a different error which is caused by your second process flow resource being a numeric resource and not referencing a task executer or group of task executers.

Also, you are not releasing the acquired crane. The resource is assigned to the "puenteinterior" label, but the Release activity is set to release a resource assigned to "token.resource".

The error message in your screenshot shows you that the load task is missing references to the item that should be loaded and the station where is should be loaded (Involved 1/2 are both NULL). In the second Load activity you are referencing "panelH" which does not exist on the token.
