Use the debugger.
Start by putting a breakpoint on "line 619" of your file, and run your application in the debugger. when it reaches the line, it will pause and let you look at what is happening.
Start on the left of the line, and check exactly what each part of the commend contains. You are looking for which bit of what you wrote contains a
null
value.
In this case:
Admin_WebSite_EditControl.LoadHeaders();
It's most likely that
Admin_WebSite_EditControl
has no value set, for some reason (but without the actual code, your data, and running it we can't tell)
When you know which value is
null
, you can start looking back through your code to find out
why it's not set. But we can't do that for you!