javascript on widget admin page

Hi,
I’m writing a plugin, and this plugin will have a widget that have some options.
If one option is checked, i want to ask the user for filling a text input, and hide this input text if the option is not checked.

Here is the code :
the form looks like these :

<input type="checkbox" onclick="javacript:myFunc();" />
<div id="toHide"><input .../></div>

the js function is correctly loaded.

function myFunc(){
 jQuery("#toHide").show();
}

and it does not work.
if i replace “jQuery” with $, firebug tells me that $ is not a function,
I don’t understant why … does anybody have an idea ?

regards

mimiz