php初学者求教

include_once("sql_connect.php");
include_once("my_msg.php");
?>
<?
if($_POST['id']=='' or $_POST['passwd']==''){
        my_msg("不可空白","login.html");
}
$result=mysql_query($sqlstr,$link);
$sqlstr="select * from member where id = '"$_POST['user_id']"'and passwd = '"$_POST['user_passwd']"'";
if($mysql_num_rows($result)==0){
        my_msg("登陆失败，重新登录","login.html");
}else{
        my_msg("登陆成功","main.html");
}
mysql_free_result($result);
mysql_close($link);
?>
提示错误Parse error: syntax error, unexpected T_VARIABLE in /usr/local/apache/htdocs/member/login_chk.php on line 10
就是这行$sqlstr="select * from member where id = '"$_POST['user_id']"'and passwd = '"$_POST['user_passwd']"'";
哪里语法不对么
PS：我再用户注册的界面也写了个，就是判断数据库里是否有这个用户，会不会是这个问题