Error using tinymce plugin

Error using tinymce plugin

An error is coming from jquery.validate.js[dynamic] file when I have
tinymce editor boxes on the page.
Please please help. I have no idea why I am getting this error, but I have
to deliver the project tomorrow.
Here is the error ; 'object does not support this property or method'
classRules: function(element) {
var rules = {};
var classes = $(element).attr('class');
classes && $.each(classes.split(' '), function() {
if (this in $.validator.classRuleSettings) {
$.extend(rules, $.validator.classRuleSettings[this]);
}
});
return rules;
},