Currently trying to help on this question - but stumbled across a very strange problem:
When trying to add conditional formatting on overlapping ranges (in VBA), Excel 2
I can see a problem in Produce1004() :
A1 has 2 format conditions and A2 has 1 format condition.
Range("A1:A2").FormatConditions.Count gives the count for A1, FormatConditions(2) doesn't exist for A2, hence the error.
But for ProduceError9() the number of format conditions is the same for A1 and A2.
With a little experimentation, I can explain this by deducing that the range is stored with the format condition (setting the font for [A1].FormatCondition(3) also fails). One must change the format for the range for which the format condition was defined.
Presumably, Excel 2010 improves on this situation by splitting a format condition on the fly.