수량에 증가/감소 표시 안보임

// 선택된 옵션 출력
function add_sel_option(type, id, option, price, stock)
{
    var item_code = $("input[name='it_id[]']").val();
    var opt = "";
    var li_class = "sit_opt_list";
    if(type)
        li_class = "sit_spl_list";

    var opt_prc;
    if(parseInt(price) >= 0)
        opt_prc = "(+"+number_format(String(price))+"원)";
    else
        opt_prc = "("+number_format(String(price))+"원)";

    opt += "<li class=\""+li_class+"\">";
    opt += "<input type=\"hidden\" name=\"io_type["+item_code+"][]\" value=\""+type+"\">";
    opt += "<input type=\"hidden\" name=\"io_id["+item_code+"][]\" value=\""+id+"\">";
    opt += "<input type=\"hidden\" name=\"io_value["+item_code+"][]\" value=\""+option+"\">";
    opt += "<input type=\"hidden\" class=\"io_price\" value=\""+price+"\">";
    opt += "<input type=\"hidden\" class=\"io_stock\" value=\""+stock+"\">";
    opt += "<span class=\"sit_opt_subj\">"+option+"</span>";
    opt += "<span class=\"sit_opt_prc\">"+opt_prc+"</span>";
    opt += "<div><input type=\"text\" name=\"ct_qty["+item_code+"][]\" value=\"1\" class=\"frm_input\" size=\"5\">";
    opt += "<button type=\"button\" class=\"sit_qty_plus btn_frmline\">증가</button>";
    opt += "<button type=\"button\" class=\"sit_qty_minus btn_frmline\">감소</button>";
    opt += "<button type=\"button\" class=\"sit_opt_del btn_frmline\">삭제</button></div>";
    opt += "</li>";