I cannot think how to do this at the moment with Data Validation.
Others may give you a VBA solution
Meanwhile, how about using Conditional Formatting ?
With B9 as the active cell use this rule: =COUNTA(A10,13)<1 and set a fill
color to alert the user of an error.
best wishes
--
Bernard V Liengme
Microsoft Excel MVP
http://people.stfx.ca/bliengme
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"collyer3" wrote in message
...
I am trying to put a validation into a cell that would refer to two other
cells. I want to make it so if I try to type text into B9 cell, I either
have
to put an X in cell A10 or A13 first. I sure there's a way to do this, but
I
can't figure it out. Any ideas?