Parameter to be passed to conroller method using jquery

Hi,
I am working on MVC application.I have a method in controller as below:

public ActionResult LogOn(string viewAction)
        {
            if (string.IsNullOrEmpty(viewAction))
                return View();
            else
                return null;
        }

 
Based on the viewAction i want to perform some action but this viewAction never gets initialised.I am using jquery ajax to pass parameters as below:

function Navigate(action) {
    
    $.ajax({ url: customerIdURL, data: { viewAction: "action"} });
} 

But the problem is that viewAction is always null..Please help me out.