Follow these two approaches until the defect is addressed.
1). Create the WSDL file manually first, then implement the operation in process. Manually create the WSDL and then implement the operations. Check the Input of activity. You should see the request parameter being populated.
2). Repair the BW project (Right click on project --> Refactor --> Repair BussinessWorks Projects). After refactoring, the project request parameters are shown in Input instead of Response.
After using the above you will able to see the correct request parameter in the Input of activity.