Thanks for posting.
Are you importing via a script/button or via File > Import records?
Try importing via File > Import. After selecting the source file (your excel file) and get to the Import Mapping window, can you verify that arrows icons are pointing from the source field to the specified target field? There should be a field mapping key in the lower right corner of the window to serve as a guide. The arrows indicate that the data from the source field will be imported into the specified target field. If needed, you can click on the current icon to cycle through the options until the arrow icon appears.
Also, are you adding new records or updating current records?
Sorry, I should have been clear. I am importing from the File -> Import menu, not a script. And I have done the field mapping and checked the arrow to move the data into FMP. Set to adding new records. And I've tried performing and not performing auto-enter actions. I see no field type mis-matches (I don't have any date fields in the source file, for example, just text and numbers). I have a bit of experience with FMP so the basics are covered. I've even read various articles or threads about this problem (lack of access priviledges (checked for both source and destination files), validation problems, etc.). Nothing has worked yet.
Only thing I can think of is the source file was created in Excel, but I'm using OpenOffice's Calc (though I'm using the .xls/Excel file type when I save the file). So I went back to the original Excel file that was emailed to me and tried importing that. Same problem.
BTW, this is on a Mac running Snow Leopard.
Ahhh. Egg on my face. I just found one field that I don't often use that was set to Always validate as not empty, but I wasn't importing anything into it. Hence the failure. Oh, well, at least I figured it out. Thanks again for the help.