Ajax.ActionLink not working properly with onBegin parameter

I have function that is called in "onBegin" ajax option of ajax.actionlink

function cancelAction() {$.ajax({
        data: { p: "test", z: "value" },
        url: '@Url.Action("DoSomething", "TestCtlr")',
        type: "GET",
        dataType: "json",
        success: function (data) {
            if (data.do == 0) {
                 // do something
            }

            else {
                alert("error message");
            }

        },

    }
    )}
return false;
}

and ajax.actionlink

@Ajax.ActionLink("Click here",//link text"Insert",// action name"Projects",// controllernew{ poz = item.itemID.ToString()},// route values newAjaxOptions(){HttpMethod="GET",UpdateTargetID="PrjDiv",OnBegin="cancelAction",OnSuccess="Initiate_Dialog"},// ajax optionsnew{@class="openDialog",@id= item.idemID.ToString()}//htmlAttributes)

Click on ajax.actionlink should check in database (onbegin) if there's record with parameters p and z (data) and if there's none, to call jquery ui dialog (Initiate_Dialog) to insert record in database. If record in database exists, action should be canceled ("cancelAction")

Problem is with "//do something part" of code.

I tried to put 

$.ajax(this.url)

$.ajax(this.href) there, to continue with my function, but it's not working.

Can someone help me with this?