Difference in firmware version.

Upgrade the software to the latest version. See procedure "Software update via Communicator (DC update companion)".

LDM 2 did not switch on or not all power parts are detected.

Check if the +24 V and +36 V modules are in their correct slot (2–3 and 2–5 respectively). Correct their positions if necessary. See procedure "Replacing the +24V module".

Bad wiring connection

Check / reseat the cables between LDM 2 and the LCB.