move_uploaded_file（）错误

<form action="add_juyuan_.php" method="post" enctype="multipart/form-data" name="frm">
<input name="fle" type="file" id="fl1">
<input type="submit" value="submit">
</form>

提交后
$f =$HTTP_POST_FILES["fl1"];//从网页里得到文件。
$dest_dir = "photo";//设定上传得目录

$file_name = explode(".",$f['name']);//按照 . 号分离文件名。这样你可以重命名文件，避免重名。

//echo $file_name[0]."<br>";//测试用语句
//echo $file_name[1]."<br>";

$dest = $dest_dir . '/' . time().".".$file_name[1];//设定上传目录和文件名。
echo $dest;
$r =move_uploaded_file($f['tmp_name'],$dest);



错误：Warning: move_uploaded_file(photo/1248771000.jpg) [function.move-uploaded-file]: failed to open stream: No such file or directory in C:\AppServ\www\tianyiwangguo\tianyileyuan\main\guanlijuyuan\add_juyuan_.php on line 26

Warning: move_uploaded_file() [function.move-uploaded-file]: Unable to move 'C:\WINDOWS\TEMP\php143.tmp' to 'photo/1248771000.jpg' in C:\AppServ\www\tianyiwangguo\tianyileyuan\main\guanlijuyuan\add_juyuan_.php on line 26