ComponentShipoutBalance{b **in** B: b <> ‘lowqfuel’,t **in** T: t>0}: #all of components produced are shippout

**sum**{i **in** I, j **in** J}u[i,j,t]*A[j,b,i] = u2[b,t];

There is something wrong in this part : {b **in** B: b <> ‘lowqfuel’,t **in** T: t>0}. I tried many different ways but did not work. Please help me!!!