ERROR : Placement area is zero. on non-rectangle floorplan

Please help, I could run through all Place and route tasks if my floor plan started with rectangular 4 sided
but I tried started with "L" shaped floorplan with area defined in top.def
we could see netlist and def read successfully, see the picture below

But when I ran create_fp_placement
an ERROR popped up:
*** Performing global placement...
Transferring Data From Milkyway...
Number of plan group pins = 0
ERROR : Placement area is zero.
Error: Failed to create placement netlist. (VFP-001)
Global placement did not complete

Please help

man VFP-001

Thank you, for the reply
What could I do to make the area not zero?
Rectangular floorplan had no problem at create_fp_placement stage