Read values from xls table with openoffice calc

Hello,

we have an existing desktop test which reads values out of an Excel file (.xls) via ddt. It works fine when Excel is installed. However if we use Openoffice Calc, some values are read fine, some show up with value '0' and some are empty.

We have to use Openoffice because we are using VMs as testing machines and don't have a valid MS Office license.

Any ideas how we get the tests to complete successfully?

Thanks

Peter