Yes, they're clearly cross-sheet links, not
cross-workbook links.

That particular reference http://www.ozgrid.com/forum/showthread.php?t=86436
is a little obscure. The person asking the question is trying to put R1C1
formulas into cells without using .FormulaR1C1. I doubt that Excel would
ever be able to cope successfully with that. It needs to be told that the
formula it's being given is R1C1 format, or else it just won't know.

You're using column-letter/row-number format, which won't present the same
problem.

However, you SHOULD be using .Formula anyway - to remind yourself that
you're inserting a formula, if nothing else. If it helps it work better, so
much the better.