Thank you for your post.
The files created by the new iWork applications are actually bundles. Beginning with Mac OS X 10.5, developers could now put several files into a folder and turn it into a bundle, so that it looks like a single file. FileMaker Error Code 732 equates to "The file cannot be inserted because it contains other files". To see the content of a bundle, right-click the file and select "Show Package Contents".
And as was suggested in another thread on this issue, the work around is to zip the bundle as that produces a single file that can be inserted.