PHP Include Path Not Found
===

I'm facing a problem when I'm trying to include a certain file.
When I try to load the file I face this error :

    failed to open stream: No such file or directory in ...

On the other hand , a `<a href="/wT/sys/background.php">background</a>` sends me directly to the file I want to include ( not the source code of it , but the output)

How come the include function cannot access the file via the given path but I can access it using a href ? 
*I need to get the source code of the file , not only the output , otherwise I'd just include the http://.... path 
*I run the php code on localhost,  if it matters

I also tried to chechk whether I need to reconfigure the php.ini file but I didn't find anything useful ( Include url is allowed altough , as I said , I don't need to use it)


Any suggestion would be helpful,
Thanks in advance 