There are no child objects - ASP.net Jquery ajax post

[mimosta]

The error is caused by data section i suppose but i could not find a solutionThe post fails and the error displayed at firefox firebug is\[code\]There are no child objects\[/code\]Here the code\[code\] var PostData = 'http://stackoverflow.com/questions/14087560/1'; jQuery.ajax({ type: "POST", url: "myASM.asmx/SetOff", data: PostData, async: true, contentType: "application/json; charset=utf-8", dataType: "json" });\[/code\]Here the web method\[code\][WebMethod]public void SetOff(string prefixText){ HttpContext.Current.Session["SetDisplay"] = prefixText;}\[/code\]