Unable to set a subscription on a customer

Hello,

I've been beating my head against this platform all day trying to figure out how to set a subscription to 'subscribed' for a customer. 
From the documentation:

[INDENT]SubscriptionsList
The subscriptionsList sublist on the Customer record can be updated. Use the replaceAll flag to update specific lines in this sublist, using subscription as the key. Be aware that Web services updates to this sublist follow the logic that is permitted in the NetSuite UI. Once an entity is unsubscribed from a category, only the entity itself can re-subscribe.[/INDENT]

The obvious attempt here was to set 'subscribed' to 'true' on the particular subscriptionList subscription and set the replaceAll to 'true'.  While it sets the value, it is not saved when I update the customer.