From which table would you compute your statistics?
It is the Cross table
As long as they are in the portal, you can compute statistics with summary fields. A summary field from the portal's table can be placed inside a filtered portal and the statistics computed by the summary fields will be controlled by the portal filter. So maybe a filtered portal would work.
Thank you for your answers!
Everything works now. I randomly confound number and text field. After that rest data were in my multiple used field. After erasing these data, everything works as it should.