postback action is not getting triggered on MessageModel cards

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In my custom component, i am calling one rest api to fetch the data and then putting into cards with actions on each card (no global action) but i am clicking on any card, it is not triggering any action button and simply moving to next state. i.e. it is supposed to call my custom component where i am handling if postback/ textReceived things as it has been described in "cmmcards" sample by Frank, but in my case it is not getting called.

Not able to figure out why it is not getting triggerd? I have integrated "cmmcardssample" by frank, which is working fine but not mine.