How do I make conference calls on Lumia 920 with Cyan update?

[Pulkit Gambhir]

I am unable to make conference calls after Lumia Cyan Update. After adding another call, Merge call button gets activated but pressing it does not make a conference and only a single call can be handled keeping other on hold. Able to swap though between them but cannot merge. using Lumia 920 CV India with Lumia Cyan PfD 8.1.1.