Upload file size problem

Hi, can anybody help me?
I have this simple code to upload file. But I can upload only file about 6 mb. How to upload greater files? If I uploaded greater file, browser wrote that page cannot be displayed (as the site doesn't exist).
I tried modify php.ini -> upload_max_filesize = 20M (standard was 2M I mean), but nothing happens (
Thanks for all replyes, Ninja

code:

select_file.php

<form action="upload.php" method="post" enctype="multipart/form-data">
Send file: <input type="File" name="soubor"><br>
<input type="Submit"><br>
</form>

upload.php

<?
if (copy($soubor, "uploaded_file.ext")) {
echo "Operation succesfull";
}
else {
echo "Operation failed";
}
unlink($soubor);
?>

it could be that your script is running over its max execution time. try changing that in your php.ini file and see what happens

it can also be that memory maximum is reached... i think it is also default to 8mb