SAP Message /ISDFPS/PM034 - You can only assign master equipment

Diagnosis
You have selected equipment or functional locations in thestatus board. However, only master equipment can be assigned toforce elements.

System Response
The system issues an error message.
The selected equipment or functional locations are not assigned to theforce element. Any master equipment you selected is assigned.

Procedure
Call up the status board again. Ensure that you select masterequipment only.