Hi Vamsi Krishna,
First, if you can I'd suggest you change the Forge Component you selected for the post, as it is currently unrelated to the SampleReactiveTaskbox component.
Second, have you checked this how-to on using the Taskbox in Reactive apps? Maybe you're missing something? or maybe you're not logged in as the right user (and so you don't have any tasks available)?
Hope this helps!