# The class or interface of MouseEvent could not be loaded

**URL:** https://forum.kirupa.com/t/the-class-or-interface-of-mouseevent-could-not-be-loaded/327003
**Category:** Uncategorized
**Created:** [January 30, 2012, 11:19am UTC](https://forum.kirupa.com/t/the-class-or-interface-of-mouseevent-could-not-be-loaded/327003 "2012-01-30T11:19:45Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![invalid](https://avatars.discourse-cdn.com/v4/letter/i/d6d6ee/32.png) [@invalid](https://forum.kirupa.com/u/invalid)
#### Post date: [January 30, 2012, 11:19am UTC](https://forum.kirupa.com/t/the-class-or-interface-of-mouseevent-could-not-be-loaded/327003/1 "2012-01-30T11:19:45Z")

</div>

Hi! I am new in flash. I am using Flash CS4 - AS2.

I am currently doing this gallery with prev and next button. But i got this error message…  
“The class or interface of MouseEvent could not be loaded.” It says that i am having a problem with the functions that I have.

stop();

btn1.addEventListener(MouseEvent.CLICK,backward);  
btn2.addEventListener(MouseEvent.CLICK,forward);

function forward(event:MouseEvent){  
if(this.currentFrame == this.totalFrames){  
gotoAndStop(1);  
}  
else{  
nextFrame();  
}  
}

function backward(event:MouseEvent){  
if(this.currentFrame == 1){  
gotoAndStop(this.totalFrames);  
}  
else{  
prevFrame();  
}  
}

How can I resolve this? thanks!