Hi Krishna,
Try this way to get it assigned , when you create the PM/CS order & save it the system should pick up
the available resource at based on the availability instead of assigning through the planning
board (/MRSS/PLBOORGSRV). Now question comes over here is the availability is there for the same
resource. Before going ahead just check if its working for concrete slot assignment ? If that works it
means there is no issue with you availability, RFC can be issue some time just delete the que.
Please update once you get solution