Affiliate Not Populating on InterUnit Billing Accounting Entries

I'm fairly new to the InterUnit Billing functionality in the Billing module, but was under the assumption that if ChartField and Inter/IntraUnit configuration is properly set up that the accounting entry for the anchor BU should include a value in the Affiliate field for the BU being billed.  The remainder of the accounting entry and corresponding intercompany entries appear to be correct.  Could somebody please confirm the following: 

1. Should Affiliate get populated if the system is configured properly?
2. If the answer to #1 is yes, what might the issue(s) be leading to Affiliate not getting populated?

Thanks in advance.