Solved
Thanks Rao,
But my content type was already application/json. I got the solution for this issue. There is a setting in Test case options with check box as "Diaply OK Result". If I unchecked it, I am able to see request and response.
I found solution to uncheck "Search preceding TestSteps for property values" in TestCase options.
But, from another hand, this settings can be needed sometimes.