Excel board? Outlook board??

I'm trying to import some Excel data into Calendar on Outlook but failing miserably. Each time I run through the import procedure, I get a message telling me "An ODBC error has occurred in the MS Excel translator while opening a file to build a data map. [Microsoft][ODBC Excel Driver] Too many fields defined"

I've recreated the named range and renamed the column headings to something shorter, but still nothing. If I cut and paste this range into a new worksheet and recreate a named range then try importing, it works fine.

Any ideas?