Task is getting completed in workflow without approval

Dear Experts,

I wanted to show table in the workitem, so i designed module pool screen & am calling the screen in the dialog task. I have designed table control & Approve , Reject buttons on screen.

Table is showing the data but once the workitem is opened without Approve or Reject work item is getting completed, I want to keep the workitem in the inbox until its getting Approved or Rejected.

Please Help.

Thanks & Regards,

Bhushan