web service not called

[krispaks]

----------JavaScript snippet---------
function timevalidation_OnBlur() {

var stime = document.getElementById('ctl00$LatitudeContentPlaceHolder$FormView1$TsStartTimeTextBox');
var etime = document.getElementById('ctl00$LatitudeContentPlaceHolder$FormView1$TsEndTimeTextBox');

var stimeval = stime.value;
var etimeval = etime.value;

oAjax = new ActiveXObject('Microsoft.XMLHTTP');
oAjax.onreadystatechange = ProcessResponseTimeValidation;
oAjax.open("POST",oValidateURL);
oAjax.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
oAjax.send("start=" + stimeval + "&end=" + etimeval);

return;
}
----------JavaScript---------

oValidateURL - "http://localhost/Latiweb201/Webservices/Validations.asmx/CheckTime"

above is a javascript function... what its trying to do is get the values from 2 certain control on my page and then use the values as parameters for a webservice... my problem is that the webservice is not called... why is this??? need some help...