Solver problems
 

Hi all,

I've used solver successfully many times in the past but I'm strugging
to understand the results in this case. Recently I built a spreadsheet
to optimize material sourcing. I have a constraint that the quantity
cells must be =0, yet solver's solution includes 2 cells with negative
values. Also, unless I lead it in the right direction with certain
inputs, it returns a solution that I know to be less than optimum.
I've double (and triple) checked input cell ranges and all constraints.

Any suggestions would be greatly appreciated.

Mike