Problem with equation 3 cost calculation

Hello everybody,
I am trying to maximize profit. The objective function for profit maximization is given Profit = (Revenue - Cost). Equation for profit and revenue both are working , but the main problem is with the cost equation. Cost equation output is zero. Although it gives feasible objective value which is wrong. Can you please help me to sort out this problem.
Code file is attached.
Kind regards.
OPF_9_bus_06_12_2018.gms (7.3 KB)