sum+sum equation issue in GAMS

Question

I defined the following equation to calculate the sum of total power consumed by the system:

TotalPower.. systemPower =e= sum(J,P(J)) + sum(I,CP(I));

However, the variable systemPower gets only the result of the second sum and not both!. The declaration of P(J) is as following:

P.LO(I)=0;

P.up(I)=100;

P.l('i1')=2;

P.l('i2')=3;

Please, Can any one explain why I get the result of a single sum? How I can do to get both?. I tried also to separate them in different values but yet I get the same result.

Thank you in advance.

Answer 1

I though it is a good idea to share this it might help someone else. I used a variable directly instead of an equation and I put it in the following form and it worked.

systemPower.l = sum(I,P.l(I))+sum(I,CP(I));