When you compare the list of fields you see above to the fields you've defined in this table, are the missing field names for fields you have defined but aren't listed in the field mapping dialog or are all your defined fields listed, but the blank field names are in addition to what you've defined?
The blank field names are in addition to what I have defined.
Have you tried doing a complete recover of your file (not just a consistency check)? I'm wondering if your FileMaker file might be damaged. Even if the recover reports "no problems found" test the recovered copy to see if you get the same result.
You might also try out a third party utility called FMDiff to check out your file.
Yes, in first place. I get the same results with recovered copy, clone or compressed copy. Tried FMDiff which detected general errors but no detailed report available with FMDiff demo version. Any other ideas ?
Recover isn't perfect. Given that the FMDIff demo reports "general errors" it's possible your file is indeed damaged which would explain the strange File mapping dialog you've posted.
Do you have an older backup file you can try?
You might also try creating a simple file with enough fields to match the columns in your spreadsheet and importing into that file. If that brand new file shows the same problem, perhaps your spreadsheet has a problem, but I suspect trouble with your file is more likely thant trouble with the spreadsheet at this point.
If you don't have a clean back up copy and your file is fairly complex, you may want to spend the $$ to get a full up copy of FMDiff to help you repair your file by deleting and rebuilding just those sections of the file that are damaged.