Why does Export not use whr-files for table splitting?

Dear all,

I created some WHR-files for table splitting and they are stored in the directory /EXPORT/DATA.

When I start the export these files are not used.

When I copy the WHR-files to /EXPORT/ABAP/DATA the additional export jobs are started but the are failing because the STR-files are missing.

How are the STR-files created?

Thanks for your help

Carsten