As we've mentioned before, there are many problems with the kind of code you (cyberwolf) posted.
First of all, $License will only exist if 1) register_globals is off *AND* the "License" input field was submitted.
If the checkbox doesn't exist, then $License doesn't exist either. The first time you attempt to access $License, PHP will throw a NOTICE level warning that you're attempting to access the value of a nonexistant variable. This is the "undefined variable" warning you see if error_reporting is E_ALL.
PHP will create this variable and give it a default empty value. For strings, this value is interpreted as the empty string (""). For numbers, it's zero. For booleans, it's FALSE.
Therefore, empty($License) will return true if License wasn't submitted, only because PHP creates it. That also means that assigning the empty string to it is pointless -- PHP already created it with the value of the empty string.
I harp on this issue because PHP has (for a couple years now) uses default configuration settings which would prevent your script from working. As Rich and I have posted countless times, the proper way to do it is:
$License = isset($_POST['License'])? $_POST['License'] : "";
The use of isset() prevents undefined variable warnings from being logged.