I have the Billing module 2.0.5. I have created a new installation in a multi server setup following the instructions found HERE and I tried to install my Billing Module. It tells me that the server has to be at least 3.1 and then it fails because my ispconfig version is 3.2. So I went into the update.php and changed the requirement to 3.2 instead and then the update worked out. With that said, now when I am trying to create an invoice, it doen't save the Items into the list. So there are some issues going on here. What do I need to do to fix my billing module? Cheers!