Cause

The user-defined property '<x>' to be imported at the PLC card with the device identification '<y>' is unknown since the parts data for the PLC card in the parts management is not up-to-date.

Solutions

Possibility 1

1. Ask the manufacturer whether an updated part with the reported property is available.
2. If yes, import the part and assign it to the PLC card.

Possibility 2

1. In the parts management add the missing user-defined property at the part.
2. Then assign the part to the PLC card.
3. Import the PLC data again.