Hi Erick,
the SAP note wasn't relevant for our system but the parameter settings did it.
Thank you very much. You made my day. 
Best regards.
Ben
Addition: I don't know why SAP is doing it with a user parameter. Cause of that: To be independent from the parameter I did a modification of CL_CHTMLB_CONFIG_TAB_EXCEL_EXP=>CREATE_BUTTON_SCRIPT. There the user parameter is read. With my own customzing I can now switch easily between the SAP standard (using the parameter) and our choice (always to have a relative call).
