请高手帮我解决一下这个问题：为什么DO循环命令老是编译错误？

dinghua2002

这一段Grip程序是实现法兰的参数化建模的，但是编译时老是提示错误，请高手指点！
程序如下：
NUMBER/D,D1,D2,D3,D4,h,h2,n,mat(12),i
ENTITY/ent(20),solid(100)
ufargs/D,D1,D2,D3,D4,h,h2,n
ent(1)=LINE/D1/2,0,0,D1/2,h,0
ent(2)=LINE/D1/2,h,0,D2/2,h,0
ent(3)=LINE/D2/2,h,0,D2/2,h-h2,0
ent(4)=LINE/D2/2,h-h2,0,D/2,h-h2,0
ent(5)=LINE/D/2,h-h2,0,D/2,0,0
ent(6)=LINE/D/2,0,0,D1/2,0,0
solid(1)=SOLREV/ent(1..6),ORIGIN,0,0,0,ATANGL,360,AXIS,0,1,0
solid(2)=SOLCYL/ORIGIN,D3/2,0,0,HEIGHT,h-h2,DIAMTR,D4,AXIS,0,1,0,IFERR,stop:
mat=MATRIX/ZXROT,360/n
DO/120:,i,1,n-1
solid(i+2)=TRANSF/mat,solid(i+1)
120:
SUBTRA/solid(1),WITH,solid(2..n+1)
MASK/3
BLANK/ALL
stop:
halt
编译错误有两处：在第13行("DO/120...")与15行处("120")提示：invalid character

dinghua2002