I've got some PHP download script. Its last two lines are these:
header("Content-Length: ". @filesize($filename));
Since you are already ignoring PHP warnings with
@, I guess you could also ignore the NetBeans warnings.
More seriously, you should of course fix the problem :
@warning suppressors behind your function calls
$filenameexists and if you have the right to read from it before trying to read the size and output its content