# Document class must be on first frame!? .. Error #1009

**URL:** <https://forum.kirupa.com/t/document-class-must-be-on-first-frame-error-1009/271765>\
**Category:** Uncategorized\
**Created:** [September 28, 2008, 3:47am UTC](https://forum.kirupa.com/t/document-class-must-be-on-first-frame-error-1009/271765 "2008-09-28T03:47:58Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![54321](https://avatars.discourse-cdn.com/v4/letter/5/7993a0/32.png) [@54321](https://forum.kirupa.com/u/54321)\
**Post date:** [September 28, 2008, 3:47am UTC](https://forum.kirupa.com/t/document-class-must-be-on-first-frame-error-1009/271765/1 "2008-09-28T03:47:58Z")

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Hey, I have a project starting at frame one and I have a document class attached to my project. I found a working preloader thing to have but when I move the project one frame ahead in the main timeline suddenly the document class doesn’t work anymore 😕

This is what the “output”-properties window says:

TypeError: Error #1009: Cannot access a property or method of a null object reference.  
at classes::BackForwardClass()

appreciate it!