[Plugin: cformsII – contact form] CformsII JavaScript Error

On my website I keep on getting this persistent CformsII error:

jQuery(".cf_date").datePicker is not a function
http://domain.com/
Line 44

On that line in the source I found:

jQuery(function() { Date.format = "dd/mm/yyyy"; jQuery(".cf_date").datePicker({startDate:"01/01/1899",verticalOffset:10,horizontalOffset:5,horizontalPosition:1 } ); Date.format = "mm/dd/yyyy"; });

Which is in cforms.php
Wonder if it conflicts with another plugin..