I use a land survey spreadsheet which uses solver to minimise the contents of
a cell subject to the contents of three other cells being reduced to zero.
The content of these three cells are set to zero in the constraints menu of
solver. During the solve procedure only 2 cells reduce to zero. The errant
cell holds its original value. the cell is not protected in any way. If I add
the constraint for this cell twice to the constraints menu (thus 4
constraints instead of the necessary 3, 2 of which are the same) the cell
does reduce to zero during the solve procedure???. It does not however give
the correct answer, close but not acceptable. The problem itself is solvable
as I have done so using two other different methods. Only solver is spoiling
my day