problema con elttura e scrittura file

[techno]

lo modificato così:

$verifica=file_exists("http://playstart.netsons.org/visite.txt");
$apertura=fopen("http://playstart.netsons.org/visite.txt","r");
$leggi=fread($apertura,filesize("http://playstart.netsons.org/visite.txt"));
if($leggi==null) $leggi=1;

$leggi++;
$apertura=fopen("http://palystart.netsons.org/visite.txt","w");
fwrite($apertura,$leggi);

fclose($apertura);
if($verifica==true) echo "true";
if($verifica==false) echo "false"; 

ma mi da questo:
Warning: filesize() [function.filesize]: stat failed for http://playstart.netsons.org/visite.txt in /home/playstar/public_html/inc/global.php on line 7

Warning: fread() [function.fread]: Length parameter must be greater than 0 in /home/playstar/public_html/inc/global.php on line 7
false