Thanks Tammy for the response. I have attached the screenshot for the Onselect of Crosstab.
Initially when I run the application first time it gives me a Overall view with the Text being displayed as Overall (since I hard coded this value on Startup)as in the previous screenshot. Then when I do drill down across various rows in the crosstab the chart and the textbox gets changed perfectly.
I have two dimensions which gets combined and displays in the Text box and works fine when I select a row of crosstab(screenshot below) The issue starts When I click again on the same row it shows ALL_MEMBERS in the textbox as in my previous screenshot.
I tried with another text box just to implcitly have the Overall Amt being displayed but still the ALL_MEMBERS keeps appearing in the textbox.