Save xls to xlsm, but only a reload gives 1000000 rows

[Graaf]

When i open a xls file in excel2010 i have 65536 rows.
After SaveAs xlsm there still are 65536 rows
After closing and reopening the file, the 1000000 rows appear.

Do i have to re-open the file?

Why:
We use different EXCEL versions. The advanced users have EXCEL 2010. Our mainframe starts excel (with marcro) and imports a CSV file.
Sometimes more than 65000 lines.

The plan:
Open excel. in de "Private Sub workbook_open()" i test the EXCEL version. When de excelversion is 2007/2010, i will save the file as 'xlsm' so that i can import more thand 65000 lines.

Is it possible?

Thnx.