I created a sample BPM process to take few parameters as input and deployed this code to the integrated server.
After that I logged in to BPM workspace page and invoked the service.
However when I invoked the service it was not allowing me to input data as the input section was greyed out.
Since I have captured the screen shot of my development I went back to check the issue.
I realized I have not selected the option Editable for the data object while creating the human task flow.
I am not sure of the way how to change it post deployment so I recreated a new human task and ensured that the Editable section is selected.
I went ahead and deployed the project and now I am able to input data in the BPM process.