[SOLVED] COM RCW - ActiveX Component can't create object

I have one COM component - "ProgramA.dll" This COM component is internally referencing "ProgramB.dll", and creating an instance of underlying object as follow:

Public Sub AddData()
Dim..... 
.......
    Set objClassA = New ProgramB.clsClassA
.....
End Sub

I have added a reference of ProgramA.dll in my .NET application (and also added a reference of ProgramB in .NET app).

When I call "AddData()" method of ProgramA through my .NET application, then its failing while trying to create instance of ProgramB.clsClassA, it is giving an error saying "AcitveX component can't create object"

What could be the possible reason, or what changes I require to do?