Validator rules using remote

Validator rules using remote

The remote method of validator using one field works fine.
 
I have a LastName field in the remote rule, where I am passing FirstName and a unique identifier and the LastName for validation.
 
I add an invalid data on the form I get error message correctly.
 
I change the fields values of LastName and FirstName to valid data The parameters passed to the remote url donot change,  and error is displayed even for correct data.
 
I can't get pass this.  the code goes like this:
 
LastName:{
    required:true,
    remote:{
     url: '/CheckUniqueContact?OpenAgent',
     async: false,
     cache: false,
     data:{
      UniqueKey:$("input[name='UniqueKey']").val(),
      FirstName:$('#FirstName').val(),
      LastName:$('#LastName').val(),
            
     }
    }
   }












 
the message section has
 
LastName:{
    required: "This Firstname & LastName combination already exists please choose another name combination.",
   remote: "This Firstname & LastName combination already exists please choose another name combination."

}
 
What mistake I may be making. Also if adding an ajax  call is made for Validator.addMethod then how can i use this method with a group rule?
 
Thanks in advance