Upgrade a product with configurable options

Got a question :

We sell cloud resources and the configurable options are what set the price of the item. On a normal item ( dedicated server ), if a client wants to upgrade / downgrade their service they click the change package button and the next page they are presented is {whmcs}/upgrade.php page. On that page, they can pick to upgrade / downgrade the product and everything works just as it should.

Now, with a product that has configurable options, nothing is shown on the upgrade.php.

Any help would be good.

v.5.3.5


EDIT:

NM - Read this...
http://docs.whmcs.com/Automated_Upgr...tions_Upgrades
and this was the issue.