Billing plan factory calendar special rules (solution)

This is the solution to a problem posted on the blog on the 27th of April

http://sapqueries.blogspot.com/2007/04/billing-plan-factory-calendar-special.html

The answer is the following:

In the settings for the Date Determination Rules (transaction OVBS), you can not maintain the Time period/unit and Calendar ID fields simultaneously. You can specify one or the other but not both.

This is specified in OSS Note 830484:

"Also note that period/time unit and calendar cannot be used simultaneously in a rule for the determination of settlement periods (Note 109013). Unfortunately, this Customizing setting cannot be checked already during the entry, since these rules are not used only for the billing plan".

I changed the settings in the IMG as follows

I also changed the billing plan (Transaction OVBI) to include the Date determination rule Z3 in the Next bill. date and Dev.Bill.Date fields (screen below)

Now when creating a contract with start and end date the billing days are what you'd expect: