sum over a set /p1*p5/ Topic is solved

[Renger]

Hi Yanzhiping
You should look at the error message you get when you submit your model to gams.
It clearly states that it is expecting a '=E=', '=L=', or '=G=' in your equation. You have a '=', which is not allowed in equations (see the manual).
Cheers
Renger