Ajax Validation interfering with Ajax call

I have a registration form that uses ajax validation, with “required” rule, on all fields except UserName. This is because userName sends an ajax request when user fills in the name to check if name already exists or not i.e this functionality is outside validation rules.
Now when i fill in userName i get correct message if userName exists or not but when i submit the form, ajax validation brings the focus back to UserName (even though UserName is not a required field) and it doesn’t allows user to move ahead…
What could be the issue?
Ajax validation code is something like below:

			// Specify validation rules
			rules : {
				// The key name on the left side is the name attribute
				// of an input field. Validation rules are defined
				// on the right side
				repassword : "required",
				role : "required",
				active : "required",
				"personalInfo.name": "required",


Ajax call for checkin userName is as below

	   if($(this).val() != null && $(this).val()!='' ){
		  url: $(this).attr('url')+ "/" + $(this).val(),
		  error: handleAjaxError

Thanks In Advance!

I think i figured it out. The the culprit was the url attribute within input tag. i renamed it to url1 and validation passed. Just for reference code for input is below:
(Though the open question is “Is url a key word when it comes to ajax validation…?”

           <div id="dvalidUserName"></div> 
          <form:label path="userName">User/Login<span style="color:red">*</span></form:label>
          <form:input url1="${pageContext.request.contextPath}/userNameExists" id="userName" path="userName" name="userName"/>