Hi,
You are missing/check for completion of some of the steps which are need to see demands from PS in MRS Planning board.
Create Org unit using transactions PPOME and PPOCE.
In PPOCE, create postions of the node, create user/person to that position and assign resource under that position.
In short your Org unit node will have a hierarchy as O_S_P (Organization_Position_Person).
Then to PP01 and maintain relationship between Org unit and Postion.
Then using SA38 and program run the availability transfer report /MRSS/HCM_RPTWFMIF for the resources.
Then go to transaction /MRSS/PLBOSRV
Thanks,
Sudhakar