Two methods with different signatures, jquery is not calling correct method
<p>There are two methods <code>GetUserAssignedSystems()</code> and <code>GetUserAssignedSystems(string Id)</code>
These methods act very differently from each other.  The problem is, when I want to call <code>GetUserAssignedSystems(string Id)</code>, the parameter-less method is called.</p>

<p>Here are the methods:</p>

<pre><code>[WebMethod]
[ScriptMethod]
public IEnumerable GetUserAssignedSystems(string cacId)
{
    return Data.UserManager.GetUserAssingedSystems(cacId);
}

[WebMethod]
[ScriptMethod]
public IEnumerable GetUserAssignedSystems()
{
    //do something else
}
</code></pre>

<p>Here is the jQuery making the call:</p>

<pre><code>CallMfttService("ServiceLayer/UserManager.asmx/GetUserAssignedSystems", 
        "{'cacId':'" + $('#EditUserCacId').val() + "'}", function(result) {
            for (var userSystem in result.d) {
                $('input[UserSystemID=' + result.d[userSystem] + ']').attr(
                    'checked', 'true');
            }
        });
</code></pre>

<p>Any ideas why this method is being ignored?</p>

<p><strong>UPDATE</strong></p>

<p>Here is the code for the CallMfttService</p>

<pre><code>function CallMfttService(method, jsonParameters, successCallback, errorCallback){
if (errorCallback == undefined)
{
    errorCallback = function(xhr)
    {
        if (xhr.status == 501)
        {
            alert(xhr.statusText);
        }
        else
        {
            alert("Unexpected Error");
        }
    }
}

$.ajax({
    type: "POST",
    url: method,
    data: jsonParameters,
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: successCallback,
    error: errorCallback
});
</code></pre>

<p>}</p>
