Excel isn't my area of expertise, but I suspect that this error message might be shown when you try to append data to the bottom of a named range and where the columns don't match exactly. If you start with
Mozart - 102 - $10.99
Schumann - 204 - $5.97[/CODE]
and try to append
Bartok - 376 - $2.97 - Sonatas[/CODE]
then Monarch will struggle as the second range doesn't fit the first.
Assuming that's fixed, then try editing the Options > Export & Clipboard to vary the Excel flavour Monarch (and DataPump) are using.
Hope this helps,