Dynamic Ranges

I use the formula
=OFFSET(Sheet1!$A$1,0,0,COUNTA(Sheet1!$A:$A),1)
to define a dynamic range name (Insert - Bame - Define)

Problem:
the name is not accepted.
No error message.
The given name does not appear in the dropdown list in the formule bar.

What do I do wrong?

Excel doesn't list Dynamic Named Ranges, but you can still use them. Just click in the Name Box, type in your DNR and press [Enter]. Excel will select your range.

Regards,
Ron