这个错误怎么解？

gaozikang

MODEL:
SETS:
pt/1..20/;
jd/1..92/;
assign(pt,jd):d,x,f;
ENDSETS
DATA:
d=@file(data1.txt);
f=@file(data2.txt);
ENDDATA
min=@sum(assign(i,j):d(i,j)*x(i,j));
@for(jd(i)sum(pt(j):x(i,j))=1);
@for(pt(j)abs(@sum(jd(i):f*x(i,j))-1.4)<1.75);
@for(assign(i,j)bin(x(i,j)));
END