I want to find deviations in a data set of supposed repeating incrementing
values (00, 01, 02, ..., 253, 254, 255, 00, 01, 02 ...), in rows of 4 by 64
values, one value per cell.. I want to highlight where the incrementing
pattern is interrupted. So I do a conditional format where my Condition1 is
Formula is =B1-A1=1. That would be fine except, the gotcha is my values
aren't decimal, they are hex (00, 01, 02, ... FD, FE, FF). So I tried
Condition1 is Formula is =hex2dec(B1)-hex2dec(A1)=1.

I get this error: You may not use references to other worksheets or
workbooks for Conditional Formatting criteria.

I can do enter formulas in cells with the hex2dec(A1), but not the
conditional formatting.
thanks in advance.