format.Currency(); is not a function (.NET, JQuery Plugin)

format.Currency(); is not a function (.NET, JQuery Plugin)

Trying to use this plugin to format a currency field correctly:

<script type="text/javascript" src="scripts/jquery.formatCurrency-1.4.0.js"></script>  
Add the above line to my .aspx page
Call this in my focusout event on a texbox:

$("#ctl00_ContentPlaceHolder1_txtOwnerAmount").focusout(function () {
 $("#ctl00_ContentPlaceHolder1_txtOwnerAmount").formatCurrency();
 });
Errors out as not a function.
Double checked, have a scripts/jquery.formatCurrency-1.4.0.js file.

Any thoughts on what I am doing wrong? Thanks.

Sean