please really need help......

hi to all i really need help with some img upload errors
please help me.......

the errors are:

Warning: imagecreatefromjpeg(/artist_gallery/Hrido Khan.jpg) [function.imagecreatefromjpeg]: failed to open stream: No such file or directory in /home/username/public_html/mysite.com/music/admin/audioadmin.php on line 2757

Warning: imagesx(): supplied argument is not a valid Image resource in /home/username/public_html/mysite.com/music/admin/audioadmin.php on line 2758

Warning: imagesy(): supplied argument is not a valid Image resource in /home/username/public_html/mysite.com/music/admin/audioadmin.php on line 2759

Warning: imagecopyresized(): supplied argument is not a valid Image resource in /home/username/public_html/mysite.com/music/admin/audioadmin.php on line 2763

Warning: imagejpeg() [function.imagejpeg]: Unable to open '/artist_gallery/small-Hrido Khan.jpg' for writing: No such file or directory in /home/username/public_html/mysite.com/music/admin/audioadmin.php on line 2764

Line#2757, #2764 i was try lot to fix it i thing my directory path its right...but i don't no....
and other 2 error samething can't fixed...please help me

Error #2757

$img=ImageCreateFromJPEG($filename);

Error #2758

	$dstW=imagesx($img);

Error #2759

	$dstH=imagesy($img);

Error #2763

imagecopyresized($rimg, $img, 0, 0, 0, 0, $srcW, $srcH, $dstW, $dstH);

Error #2764

imagejpeg($rimg, $smallpath);

here is the codes

// Save Information?

		if( $HTTP_GET_VARS['save'] == 'yes' ) {

			

			$str_upload = trim(basename($HTTP_POST_FILES["userfile"]["name"]));

	       $UPLOAD_PATH = "/artist_gallery/";

		   if(@is_uploaded_file($HTTP_POST_FILES["userfile"]["tmp_name"])) {

		   	  move_uploaded_file($HTTP_POST_FILES["userfile"]["tmp_name"],ROOT_DIR.$UPLOAD_PATH.$str_upload);

	          $aid=$HTTP_POST_VARS['aid'];

	          //mysql_query("INSERT INTO avaiting_artist(id_artist,url,username) VALUES('$aid', 'artist_gallery/avaiting/$str_upload','{$_SESSION[username]}')");

	          //******************************

	          $filename=$UPLOAD_PATH.$str_upload;

	          $smallpath=substr($filename, 0, strpos($filename, strrchr($filename, "/")));

	          $twopart=substr($filename, strpos($filename, strrchr($filename, "/"))+1, strlen($filename));

	          $smallpath=$smallpath."/small-".$twopart;

	          $it=substr($filename, strlen($filename)-3, strlen($filename));

	          if ($it=="jpg") {

	            $img=ImageCreateFromJPEG($filename);

	             $dstW=imagesx($img);

	             $dstH=imagesy($img);

	             $srcW=100;

	             $srcH=100;

	             $rimg=imagecreatetruecolor($srcW, $srcH);

	             imagecopyresized($rimg, $img, 0, 0, 0, 0, $srcW, $srcH, $dstW, $dstH);

	             imagejpeg($rimg, $smallpath);

	          }

	         if ($it=="gif") {

	            $img=ImageCreateFromGIF($filename);

	            $dstW=imagesx($img);

	            $dstH=imagesy($img);

	            $srcW=100;

	            $srcH=100;

	            $rimg=imagecreatetruecolor($srcW, $srcH);

	            imagecopyresized($rimg, $img, 0, 0, 0, 0, $srcW, $srcH, $dstW, $dstH);

	            imagegif($rimg, $smallpath);

	         }

	          //******************************

		   }