Need urgent help with solver. It does not change value

Hi ppl. Need some help urgently here. Appreciate any help.

I am supposed to optimise the cost to the lowest values. As you can see, I have to fulfill the demand based on the production capabilities of the 3 factories A,B,C. I used solver but the cost doesnt change from what i already have filled in. why??

Appreciate all help.

Because your "filled in values" are an optimal solution and solver can't improve on it. If you clear the range "I13:M15" and do a rerun of solver, the optimal solution found by solver will be $78 675 so your "guessimate" of $58 200 is a much better solution as you have set the object function to minimize costs.

Question really is why can't solver find the same optimal value?

Alf