How to display a Model Box as Rails response

I am using jquery colorbox plugin as my popup/modal dialog box solution
in my site. When I give a js response to client, I want to open a popup
modal dialog box as the response. I wrote the following code in my
response1.js.erb just to test the creation of popup box


I am getting the Javascript response correctly from server but while it
is getting executed on the browser, firebug reports error like

$.colorbox() is not a function

how else can I do the task? please help. All my related
javascripts(jquery,colorbox) are getting loaded properly when the page
loads (i checked the page source html file)