Pcell --- create donut depend on conic sides

Hi all

    I just want to construct one PCell with "donut" shapes,but encountered some problems.
All that i want to do is to get one donut owned its' conic sides ,and the value of conic sides is set from Layer Editing(Option -> Layout Editor... -> Conic Sides)    
I try to get the donut with conic sides is '20'(default:20) using SKILL function called "dbLayerAndNot", but finally i got
a donut with conic sides is '24'.
I have post my SKILL code to you as below.

Is any one can give me some suggestion, or knows any founction or method can let me control the conic sides of donut in PCell?

SKLLL code:

;---start

inside = Radius/2
outside = Radius/2+Width
(pcLayer = 9)
(pcPurpose = "drawing")
(pcInst = dbCreateDonut(pcCellView
          list(pcLayer pcPurpose)
           (0.0:0.0) outside inside
))

(pcLayer = 11)
(pcPurpose = "drawing")
(shape = dbCreatePolygon(pcCellView
         list(pcLayer pcPurpose)
         list(-outside:0.0 outside:0.0 outside:-outside -outside:-outside)
))

   dbLayerAndNot(pcCellView "met1" list(pcInst) list(shape))
   dbDeleteObject(pcInst)
   dbDeleteObject(shape)

;--- end

ps:
   Virtuoso Layout Editor, version is 5.10.41