this.callback is not a function

new ajax.xhr.Request('commentadd.jsp', params, searchmember('<%=groupPlanDto.getG_id()%>'), 'POST');

---

function searchmember(g_id) {
        var params = "g_id=" + g_id;
        sendRequest("/railro/admin", params, receiveList, "GET");
    }

in this code "this.callback is not a function" is occurered

Is this impossible? -> searchmember('<%=groupPlanDto.getG_id()%>')

But I have to need "g_id" when I move to searchmember How can I solve this problem...?