a little confusion

[half flung pie]

I'm trying to use mysqldump and have the following PHP code

	$username = "root";
	$password = "password";
	$db = "mydb";
	$backpath = "C:\inetpub\wwwroot\site\backups\\" . $db . "-backup-" . date("Y-m-d-H-i-s") . ".sql";
	$exec = "mysqldump --user={$username} --password={$password} --quick --add-drop-table --add-locks --extended-insert --lock-tables --all {$db} > $backpath";
	exec($exec);

This code apparently does not work though. There are no files saved in that directory after running the code. However, if I run

mysqldump --user=root --password=password --quick --add-drop-table --add-locks --extended-insert --lock-tables --all mydb > C:\inetpub\wwwroot\site\backups\mydb-backup-2010-07-12-14-53-50.sql

in a command prompt, it works just fine. Any ideas why it won't run through PHP?

Also, safe_mode = Off in my php.ini file