Apply Date filter in Odata Query

Hi Experts,

here is my Query

var oDataQuery = "f1_workorderSet$select=f1_workorderId,f1_WorkOrderType,f1_ServiceAccount

&$expand=f1_account_f1_workorder_ServiceAccount&$filter=f1_WorkOrderType/Id eq (guid'" + workordertypeId + "') and f1_ServiceAccount/Id eq (guid'" + acountId + "') and $filter=createdOn gt " + datefilter + "";

where my datefilter is "datetime'2014-12-14T14:54:25Z'"  (Question : do i need to pass the variable value along with Z at the end ?)

something is wrong ..unable to get result suggest solution .

i get the above format after passing datetime to below function

function getODataUTCDateFilter(date) {

var monthString;

var rawMonth = (date.getUTCMonth() + 1).toString();

if (rawMonth.length == 1) {

monthString = "0" + rawMonth;

}

else { monthString = rawMonth; }

var dateString;

var rawDate = date.getUTCDate().toString();

if (rawDate.length == 1) {

dateString = "0" + rawDate;

}

else { dateString = rawDate; }

var hourString = date.getUTCHours().toString();

if (hourString.length == 1)

hourString = "0" + hourString;

var minuteString = date.getUTCMinutes().toString();

if (minuteString.length == 1)

minuteString = "0" + minuteString;

var secondString = date.getUTCSeconds().toString();

if (secondString.length == 1)

secondString = "0" + secondString;

var DateFilter = "datetime'";

DateFilter += date.getUTCFullYear() + "-";

DateFilter += monthString + "-";

DateFilter += dateString;

DateFilter += "T" + hourString + ":";

DateFilter += minuteString + ":";

DateFilter += secondString + "'";

return DateFilter;

}