This can be caused by a few items. 

If this is a new configuration we must make sure we've run the Update ID Mapping process in BBEC.

1. Go to the Web functional area in BBEC
2. Click Web Transactions
3. Click 'Update id mapping'

If we're still finding no results come through first verify that the query/selection in BBEC actually has results in the application.  If we find the query does have records we can validate the email and phone type mappings in BBNC to ensure we're using a valid/existing type between both BBEC and BBNC.  The rationale behind this is that BBNC has built in filters and will only return constituent records through the query that have the same mapped email/phone type in both BBEC and BBNC per it's configuration.

1. Log into BBNC as an administrator
2. Go to Administration, Sites, Settings tab
3. Scroll down to the phone types configuration.
4. Ensure that we have an email type selected, if not select one.
5. Verify the constituent records in the BBEC query have this email type on their record via the Contacts tab on the record
6. Reprocess the query/email list in BBNC

We should find that records now populate into the list successfully.  The list results in BBNC will never, typically, match 100% with the total returned records of the query in BBEC due to removal of duplicates, records marked as do not contact, and not having the correct email type.