lingo 错误29请问是怎么回事?

lingo 错误29请问是怎么回事?

model:
sets:
level/1..6/:p,z,goal;
plant/A1..A3/:b;
customer/B1..B4/:a;
routes(plant,customer):c,x;
deviation/1..12/:d1,d2;
obj(level,deviation)/1 4,2 5,3 6,3 7,3 8,3 9,4 10,5 11,6 12/:wplus,wminus;
endsets
data:
b=300 200 400;
a=200 100 450 250;
c=5 2 6 7 3 5 4 6 4 5 2 3;
ctr=?;
goal=?0;
wplus=0 0 0 0 0 0 0 0 0 1 1 1;
wminus=0 0 0 1 1 1 1 1 1 0 1 0;
enddata
p(ctr)=1;
@for(plant(i):[con1]@sum(customer(j):x(i,j))