Hi Sundeep,
I hope you are performing the Maintain Task Names and Decision Options step in the backend system. Have you also done the step Configuring the SAP Fiori Launchpad for Your Scenario-Specific Tiles as given here App Implementation: My Inbox - SAP Fiori for Request Approvals 1.0 - SAP Library? Under the tile property Parameters have you specified the scenarioID?
Regards,
Saurabh