CNAME Record

Hi,

I created a sub-domain a.example.com (works good). And I tried to create a CNAME record hello.example.com and hello.a.example.com. (CNAME record created successfully. DNS query resolves) But whenI try to open the the url hello.example.com OR hello.a.example.com in browser (theoretically it should open up the same page as a.example.com. But it just gives me a blank page.

Could you please help. what is not working here.