How to add an existing Global Condition to an application deployment type via Powershell?

Hi All,

I'm trying to add an existing Global Condition to an application deployment type via Powershell. The part I'm stuck at is running this command:

$app.DeploymentTypes[1].Requirements.Add($rule)
Cannot find an overload for "Add" and the argument count: "1".
At line:1 char:1
+ $app.DeploymentTypes[1].Requirements.Add($rule)
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (:) [], MethodException
    + FullyQualifiedErrorId : MethodCountCouldNotFindBest

I'm assuming that means that I haven't selected/set my $rule properly. I tried using this command to assign $rule to an object using the Requirements on a different deployment type:
$rule = $app.DeploymentTypes.[0].Requirements

I've looked through the article here (gallery.technet.microsoft.com/SCCM-2012-Global-Condition-2b133101#content)and tried tweaking his scripts, but it seems like each time you Create the GlobalCondition you're making a new one; what I want to do is just assign an existing one. That way, if I need to modify all of the application deployment types using that one Global Condition I can change one and have it change for all that use that (i.e. if Windows 8.2 comes out, then I don't need to check the 8.2 box on all my deployment type requirements).

How do I select an existing GlobalCondition properly so that i can assign it using the command below?
$app.DeploymentTypes[1].Requirements.Add($rule)

Thanks a ton in advance!