Hi Husin,
I have seen the exact circumstances you are encountering. When setting up our monitoring/reporting, ABAP and JAVA systems allowed for the setup of Reporting via Extractor activation. On the other hand, Web Dispatcher and TREX systems did not present themselves for activation on the Reporting tab of the Technical Monitoring guided procedure and their reporting status on the Define Scope tab remains grey. I have not been able to find any documentation from SAP on the SolMan reporting setup for Web Dispatchers, but I believe what you see regarding your Web Dispatcher instance in the Technical Monitoring setup is not out of the ordinary.
Thanks,
Jeff