There can be uncountable error cases. This page will be continuously completed with typical problems.
The first step in synchronization is to find or create a Contact or an Account. The second step creates a logging Activity object (Task or Event), connected to that Contact or Account.
If some error occurred, it will be described in error message in the call detail. Please read this article about how to get detailed error message.
In case logging works, but you are unsatisfied with, for example Task field Status - "open", you can define default values for fields. Read this manual about default field values. Unfortunately, this should make your administrator, because it can be a strategic decision.