lingo11.0 一直显示Missing right parenthesis

model:
sets:
Am/1..3/:a; Bm/1..4/:b;routes(Am,Bm):c,v;
endsets
!the objective; min=@sum(routes:c*v);
!约束条件;
@for(Am(i):@sum(Bm(j):v(i,j))<a(i);
@for(Bm(j):@sum(Am(i):v(i,j))=b(j);
data:
a=7,9,7; b=3,5,7,8;
c=12,13,10,11
10,12,14,10
14,11,15,12;
enddata
end
这个代码有什么问题？

@for(Am(i):@sum(Bm(j):v(i,j))<a(i));
@for(Bm(j):@sum(Am(i):v(i,j))=b(j));