flattening an instance and then removing certain layers

Hi,

I am trying to create an instance of a cellview in my layout (the cel view can contain one or more pcells) and then remove certain layers from it (like all the metal 2 and metal 3 layers).

The process which I am following is as follows:

1. Create an instance of the object in my cellview

2. Flatten the instance till 10 level of hierarchy (10 is a randomly chosen number, my hierarchy will not exceed 10)

3. Get the list of all the db objects in the cellview

4. delete all the shapes with layer type as metal2 or metal3

5. save and close

I am able to create the instance in my cell view and it is flattened but the shapes are not removed.

I get the following error in the console window:

.

.

dbGetq: object is a purged/freed object - db:0x21776ca2
type: nil
dbGetq: object is a purged/freed object - db:0x21776ca3
*WARNING* (DB-270063): dbDeleteObject: Invalid database object 0
dbGetq: object is a purged/freed object - db:0x21776ca3
type: nil
dbGetq: object is a purged/freed object - db:0x21776ca4
*WARNING* (DB-270063): dbDeleteObject: Invalid database object 0
dbGetq: object is a purged/freed object - db:0x21776ca4

.

.

.

Below is my code:

cellview = dbOpenCellViewByType( libraryName viewname1 "layout" "maskLayout" "w")

instA2 = dbOpenCellViewByType( libraryName viewname2 "layout" "maskLayout" "r" )

instIdA2 = dbCreateInst(cellview instA2 "inst1" list(0 0) "R0" 1)

dbFlattenInst(instIdA2 10 t t)

allShapes = cellview~>shapes

(foreach shape all_shapes

   if((member(shape~>layerName toRetain) == nil) then
       dbDeleteObject(shape)

)
)

dbClose(inst)
dbSave(cellview)
dbClose(cellview)