Hi Karthi,
Sorry for delay in my answer.
I'm not sure what is the problem but I've run your example in stackblitz with the same result, no events are showed.
If I understand an event must be shown on 2018-01-15 after pressed button SHOW, but the calendar is empty.
The same happends in my code, I've translated you code to my app with the same result, events are not showed but datasource is populated.
Do I need to call some kind of refresh after populate datasource?
Regards
Jose