Setting up metered billing with fixed monthly fee. Anyone?

[Nancy]

Hi, everyone.

I'm developing cloud hosting website based on CloudStack and Hostbill. There are few things that have kept bugging me. It's about metered billing per hr. Billing system is that customers are going to be charged by total running time of a VM X price per hr.
So, what I did was go to the pricing section in the admin area, click metered, enter 0 in both Starting QTY and Endign QTY fields and the price in the unit price field in Running VM section.  And saved changes.
And tested if it was applied by creating a VM in the client portal. But it doesn't appear in the invoice details. It should've shown hourly price in the Running VM section, but nothing. Only monthly flat fee is shown in the details.

I think I followed exactly the same way as the video Kris posted..what did I miss?   

Can anyone who knows about this help me?