Jquery ajax Split and save json response into variable - asp.net

Question

Here my Code, on sucess i need to split (data.d) and stored in variable, but it not working, any idea where am wrong ?
$("#ckAddrow").click(function () {
var abcStr = null;
var taskName = $("#ctl00_ContentPlaceHolder1_txttaskname_").val();
var sdate = $("#ctl00_ContentPlaceHolder1_txtsdate_").val();
var edate = $("#ctl00_ContentPlaceHolder1_txtedate_").val();
var hdfieldid = $("#ctl00_ContentPlaceHolder1_hdid").val();
var dataString = 'taskname=' + taskName + '&sdate=' + sdate + '&edate=' + edate + '&hfid=' + hdfieldid;
// alert(dataString);
$.ajax({
type: "POST",
url: "AutoComWebservices.asmx/insertTasksRecord",
data: "{ 'prefix': '" + dataString + "'}",
dataType: "json",
contentType: "application/json; charset=utf-8",
cache: false,
async: true,
success: function (data) {
abcStr = data.d;
alert(abcStr);
BuildTable(data.d);
// var valSplit = abcStr.split('-');
// var taskname = valSplit[0];
// var startdate = valSplit[1];
// var enddate = valSplit[2];
// var pf = valSplit[3];
// var myscopeid = valSplit[4];
// alert(taskname + " - - - " + myscopeid);
// alert(data.d)
// var getId = myscopeid;
// var abc = "<tr id='" + getId + "' class='edit_tr'><td class='edit_td'><span ID='taskName_''" + getId + "' class='lblclass'>'" + taskName + "'</span><input id='taskName_txt_''" + getId + "' class='editbox' type='text' value='" + taskName + "' /></td><td class='edit_td'><span ID='startDate_''" + getId + "' class='lblclass'>'" + sdate + "'</span><input id='startDate_txt_''" + getId + "' class='editbox sdatedp' type='text' value='" + sdate + "' /></td><td class='edit_td'><span ID='endDate_''" + getId + "' class='lblclass'>'" + edate + "'</span><input id='endDate_txt_''" + getId + "' class='editbox edatedp' type='text' value='" + edate + "' /></td></tr>";
//"<tr id=9 class=\"edit_tr"><td class="edit_td"><span ID="taskName_9" class="lblclass">dummy</span><input id="taskName_txt_9" class="editbox" type="text" value=dummy /></td><td class="edit_td"><span ID="startDate_9" class="lblclass">03/14/2013</span><input id="startDate_txt_9" class="editbox sdatedp" type="text" value=03/14/2013 /></td><td class="edit_td"><span ID="endDate_9" class="lblclass">03/30/2013</span><input id="endDate_txt_9" class="editbox edatedp" type="text" value=03/30/2013 /></td></tr>"
}
});
});
On alert(abcStr);
is shows heloo-03/19/2013-03/20/2013-138-52
further i need to split('-') and save in variables;
My webmethod code:
[WebMethod]
public string[] insertTasksRecord(string prefix)
{ List<string> d = new List<string>();
string taskname, startdate, enddate,pf;
string datastr = prefix;
string myvalue = "";
string[] val = datastr.Split('&');
string[] tname = val[0].Split('=');
taskname = tname[1];
string[] sdate = val[1].Split('=');
startdate = sdate[1];
string[] edate= val[2].Split('=');
enddate = edate[1];
string[] planid = val[3].Split('=');
pf = planid[1];
DateTime mysdate = Convert.ToDateTime(startdate);
DateTime myedate = Convert.ToDateTime(enddate);
SqlCommand cmd = new SqlCommand(myQuery, connloc);
connloc.Open();
string myscopeid = cmd.ExecuteScalar().ToString();
connloc.Close();
d.Add(string.Format("{0}-{1}-{2}-{3}-{4}",taskname, startdate, enddate,pf,myscopeid));
return d.ToArray();
}