Problem using JQuery with Zimlet

Hi guys,

I'm making an integrated Zimlet-which is meant to add a new toolbar button.
I downloaded the example Zimlet from Zimbra web site : ZCS 6.0:Zimlet Developers Guide:Example Zimlets - Zimbra :: Wiki

It worked fine until I modified the Zimlet definition file to include JQuery library:

<zimlet name="com_zimbra_example_toolbarhook" version="1.0" description="An example zimlet that adds a button to the Compose toolbar.">
<inclue>jquery.js</inclue>
<include>com_zimbra_example_toolbarhook.js</include>
<handlerObject>com_zimbra_example_toolbarhook_Hand lerObject</handlerObject>
</zimlet>

When I deploy the zimlet and use Chrome's developer tool to track the error,I keep getting this error:

Uncaught TypeError: Object visibility:hidden;border:0; has no method 'insertBefore' Zimlets-nodev_all.js:1169
_P Zimlets-nodev_all.js:1169
i.Callbacks.e Zimlets-nodev_all.js:886
i.Callbacks.Y_.fireWith Zimlets-nodev_all.js:977
G_.extend.ready

Another strange thing is it works perfectly when I use dev mode (add ?dev=1 param to URL).
Have anyone ever scoped this before?