Hi Sachin-Walunj,

The below links has the documentation highly associate with the issue you have posted above. Try them and see if the issue gets resolved:

http://community.k2.com/t5/K2-blackpearl/Object-reference-not-set-to-an-instance-of-an-objects/ta-p/90021

http://community.k2.com/t5/K2-blackpearl/Smart-Object-Error-Object-reference-not-set-to-an-instance-of-an/ta-p/82483

Best regards,

Abraham.

Hi,

It looks like the SilverlightService.asmx web service is being called when trying to add SmartObject in Create Reference – Wizard Step window (see image link: http://www.screencast.com/t/5KGiQngJL). The error seems to indicate that there is an orphaned category somewhere in the environment. Maybe, you can check each category in K2 Designer and look for any orphaned or out of synced categories.