On Windows 7, using a FileMaker Pro 11.0 v3 file, I am able to export to "Excel 95-2004 Workbooks (*.xls)". What I am doing is:
1. opening a file containing three records,
2. pulling down the File menu and selecting Export Records,
3. in the "Save as type" drop down, select: Excel 95-2004 Workbooks (*.xls),
4. name the file and click "Save",
4. bypass the "Excel Options" by clicking on "continue",
5. follow prompts to select fields to export.
Since you aren't able to export records from your database, please let me know what you are doing differently. Can provide more details on what you are doing to "convert" the Excel file to FileMaker? It would be easier to help you if I can replicate the issue you are encountering.
I just got help with this. Apparently, FM11 had been installed with a setting that prevented adding any databases. We re-installed the program with complete access and that solved the problem.