Cost Optimization for 2 plants
Answers

Hello
All the constraints have to be met for the solution to be feasible. A solution that is not feasible can not be optimal.
With Optimizer we resolve the problem in its globality. Which means we don't look for a solution plant by plant, we look for a solution that optimises the objective function.
if one of the constraints are not met, you need to find a new way to write your constraint. Because, if you leave it that way, you will have infeasiblities, which means no solution
Regards
Dihya Atmani
1 
When you are running optimizer to solve for a problem, it might stop (as in this case) if the constraints are not satisfied completely. Depending on the planar, it can stop without giving an optimal solution for the other plant as well. You will not get an optimal result. If the optimizer fails, it is not recommended to use the values it might have changed during the iterations. I will recommend to run solutions for individual plants if there are no overlap between the two.
0 
Even though more nuance would be welcome for a better understanding, I think these are the most likely reasons for your outcome:
1. Settings: Make sure that you set the optimiser to look for an optimal solution (as opposed to a "feasible" and sub optimal solution)
2. Approach: There are quite a lot of candidates to be causing the issue here:
Since you mentioned that the variables (supply and demand) are independent per Plant, I am wondering how do your constraints, other variables and objective function look like, since they could be disconnected too.
For instance; if your objective function is to minimise the total aggregated inventory cost of both plants (I assume) but you do not specify a constraint that both plants must satisfy their respective demands, the Optimiser will just assign more stock to the most "costeffective" plant, ignoring the demand of the most "expensive" one.
I hope that this "brain storm" will help you to approach your problem in a different way and get closer to a solution. Else, I am afraid that more details from your side would be necessary.
Cheers!Alex
1 
@anikdas wrote:When you are running optimizer to solve for a problem, it might stop (as in this case) if the constraints are not satisfied completely. Depending on the planar, it can stop without giving an optimal solution for the other plant as well. You will not get an optimal result. If the optimizer fails, it is not recommended to use the values it might have changed during the iterations. I will recommend to run solutions for individual plants if there are no overlap between the two.
Agree +1
0