I am trying to use the following formulas

=sumif(A2:A19,"3/0",M2:M19)/countif(A2:A19,"3/0")

=SUMIF(A2:A19,0,M2:M19)/COUNTIF(A2:A19,0)

columns A and M look as follows:
Size Post/Laser
0 1.112
0 1.099
0 1.105
0 1.111
0 1.112
0 1.116
0 1.116
3/0 1.109
3/0 1.105
3/0 1.097
3/0 1.094
3/0 1.106
3/0 1.112
3/0 1.117
3/0 1.094
3/0 1.094
3/0 1.107
3/0 1.090


In one case, the formula works beautifully. in the other case, the cell
spits back the formula. It does not give me the result. I seem to remember
having this problem before and pressing some combination of keys to get "{}"
to appear on either end of the formula and it working then, but I do not
remember the key combo.

Can anyone help? Why does this happen?

Thanks

SS