PHP文件未找到错误，但它包含该文件？

Question

I have the following code to include a file that runs some SQL and other code

if (isset($_GET["vpnadd"])) {
echo "Swapping to VPN<br />";
$filename = '/home153/sub002/sc00083-LGVN/xxx.co.uk/addmyfile.php';
require $filename;

} 

However, when I run the code, it gives an error of: error: No such file or directory

But, it does actually run the file and inserts a database record so I am not sure why it gives the file error?