Ext js 4.2 locale lang

Hello,

I'm trying to use the /locale/ext-lang-de.js to change the YES NO button in the Ext.MessageBox.confirm();

I have this in my index.html

HTML Code:

<script type="text/javascript" src="extjs/locale/ext-lang-de.js"></script>

I already googled it but I couldn't find anything.

It's kinda urgent please