There can be a number of reasons why a wire has failed to come across to the harness design. There should be a log in the output window on your harness design that gives you a summary of what happened during the synchronization process. The first thing to do would be to check that area for information on your wires.
Also, as general guidance:
- Make sure that wires and their corresponding connectors are connected (that you don't have some wires dangling)
- Make sure that both Connectors and wires in between are tagged with the right harness name