This screen shot shows the outgoing IDOC, but you have actually have a problem the incoming that is not posted.
Note 31126 - Intercompany billing - posting to vendor account using EDI
Please find the inbound idoc e.g. in BD87
or go into VF03 for your billing document, click the service for objects icon and then the distribution icon on the service for objects icon bar.
this should give you the inbound IDOC and you can directly drill into it to see the status