Quote:
Microsoft JScript runtime error: 'document.getElementById(...)' is null or not an object
You have not provided much detail and codes to look at. Still I would like to give you some idea on the error.
This error always comes, if the Element is not present inside the Document. When you try to get the Element, it says that object is null as it is absent.
If you creating the Element dynamically, then make sure that you are trying this code after the Element is created and inside the correct event.
Hope this helps you to resolve the issue.