Troubleshooting IB messages

Pardon me if i'm asking a very basic question but I do not have any experience in IB.

I just wanted to know what are all the basic steps in trouble shooting IB.

Here is the scenario: I have done a personal data change in HR8.9 and is successfully published (PERSON_BASIC_SYNC) but the same is not subscribed in CRM. I have checked all the configurations and it looks fine. Can anyone throw some light on this please?