In case you encounter this message, it means that the Postnummer hasn't been included or it hasn't been included correctly.
In order to ship orders to a Packstation with DHL Parcel, you need to set the address as follows:
Street Line 1: " Packstation " + number
Street Line 2: Postnummer
Moreover, please make sure not to include the Company name inside the recipient address for the Postfiliale.