Hi William,
Thanks for your response.
I am using ArcGIS 10.1 and C# language for developing the AddIn. I have also tried VBA code in 10.1. But no luck.
As you suggested, I tested the tool in ArcGIS 10.2 and I am getting the same results. It is population with "0" as GUID value.
I will also try to test it in VB.NET and let you know the results.
Thanks,
Mani