Assura LVS cdl file is not right

[cgikun]

Hi,all

I want to run assura lvs with cdl file and gdsii,so the cdl file is like this:
.subckt BJT_AREA40 C B E
BJT C B E bjt area=40
.ends BJT_AREA40

.subckt 1 P1 P2 P3
xBJT1 _net1 _net2 _net3 BJT_AREA40
.subckt 1
.end
Then I run completely.
But That is a question about when we use different area device ,we will get different subckt.
So I want the cdl file like this :
.subckt BJT_AREA C B E
BJT C B E bjt area=area $[area]
.ends BJT_AREA
.subckt 1 P1 P2 P3
xBJT1 _net1 _net2 _net3 BJT_AREA area=40
xBJT2 _net4 _net5 _net6 BJT_AREA area=60
.ends 1
.end
But I can not run the lvs.
So what is wrong for me ?
Please help me!
Thanks a lot !