I have a setup that (simplified slightly) looks like:

A1: 20
B1: =if(A1<50,"",A1)
C1: =isblank(B1)

C1: produces "false". Why? Isn't "" supposed to put "nothing" into a cell?

The point of all this: I want the cell to be truly blank, so that it doesn't
graph as a "zero" in a chart. (Yes, I have the option under ToolsOptions
checked, so that blank values are not plotted as zeros.) However, it is
graphing my "not quite blank" cells, generated by the above formula, as
zeros. It does skip truly blank values (if I delete the formula altogether),
but doesn't when I try to force blank values using a formula like this.

Any ideas how to get a formula to make a cell think it is blank?

Thank you,

Heidi