# CS3 to CS4 | ReferenceError: Error #1065: Variable is not defined

**URL:** <https://forum.kirupa.com/t/cs3-to-cs4-referenceerror-error-1065-variable-is-not-defined/308763>\
**Category:** flash\
**Created:** [April 29, 2010, 4:34pm UTC](https://forum.kirupa.com/t/cs3-to-cs4-referenceerror-error-1065-variable-is-not-defined/308763 "2010-04-29T16:34:59Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![BeechyBoy](https://avatars.discourse-cdn.com/v4/letter/b/8e8cbc/32.png) [@BeechyBoy](https://forum.kirupa.com/u/BeechyBoy)\
**Post date:** [April 29, 2010, 4:34pm UTC](https://forum.kirupa.com/t/cs3-to-cs4-referenceerror-error-1065-variable-is-not-defined/308763/1 "2010-04-29T16:34:59Z")

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I have seen a few posts regarding: ReferenceError: Error #1065: Variable is not defined, but none solving this issue…

I have just upgraded to CS4 from CS3. I compiled and run the projects built in CS3 and get this error on loads of MovieClip classes available in the Library.

ReferenceError: Error #1065: Variable Movieclip\_mc is not defined

Sounds like there is a difference in the compilers that is kicking this error up. I have tried creating a new central .fla document in CS4 and stil no good.

What’s going on here?