请问哪位大侠知道SLL的用法？

求助各位大侠：下面的程序运行后为什么老是出错呀？
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.numeric_std.all;
use ieee.std_logic_arith.all;
entity fdkz is
port(kongzhi:in std_logic;
   srdata:in std_logic_vector(9 downto 0);
   fddataut std_logic_vector(9 downto 0));
end;
architecture behav of fdkz is
constant fd:std_logic_vector(6 downto 0):="1100010";
begin
  process(kongzhi,srdata)
  variable data1:std_logic_vector(15 downto 0);
  variable data2:std_logic_vector(15 downto 0);
  variable data3:integer range 0 to 102300;
  variable data4:integer range 0 to 1023;
  variable data2:std_logic_vector(15 downto 0);
   begin
data1:="0000000000000000";
data2:="0000000000000000";
if (kongzhi='1') then
   for n in 6 downto 0 loop
  if (fd(n)='1') then
   data1(9 downto 0):=srdata;
   data1:=data1 sll 1;
   data2:=data2+data1;
  end if;
    end loop;
    fddata<=data2（15 downto 6);
end if;
   end process;
end;
本程序为实现输入数据移位后相加送到输出端，在QUARTUS中编译
程序运行后老是出现:can't determine definition of opertor "sll"--found 0 possible definitions
请问哪位大侠知道SLL的用法？