Hi,

Depending on the chart type you can use NA() instead of "" in your formula.
=IF( A1 < "X" , A1 , NA() )

Cheers
Andy

cybermrt wrote:
If a cell has a hidden fomula that returns a blank cell, then the chart
always reads this as a zero and plots the line as a zero?

Similarly if the cell contains a letter rather than a number, this will also
be plotted as a zero?

--

Andy Pope, Microsoft MVP - Excel
http://www.andypope.info