Hi everyone I am freshman on this,

2013 SOLIDWORKS API Help - Get, Add, Change, And Delete Cut-List Custom Properties (C#)  I have gotten to use this example and I am trying to understand how it is going on. I have DocumentManger key.

However after this

Debug.Print("Last Update Stamp: " + swDocument13.GetLastUpdateTimeStamp());

I have gotten null exeption due to swDocument10= null and swDocument13= null

How can I handle this could you help me ?