Solver not finding optimium Result

I am trying to minimize costs for our Line of Credits
We have 5 lines which charge when we use their line and when we do not use it (albeit) a smaller rate
The rates are tiered by $ amount

We need a finite amount of money H17
We cannot go over any specific credit line (c4:h4)
And need the solver to solve for the amounts needed (C17:G17) that will minimize costs (H12).