If the application cannot be obtained for testing, further details may be requested including a packet capture of the application traffic to help create a signature.
To request a custom App-ID signature for a proprietary or non-commonly used internet application:
Contact Palo Alto Networks Professional Services by reaching out to your local SE and / or accounting team. They can put you in touch with Professional Services of your region.
If an App-ID or custom App-ID signature is not working as expected, create a Support case and a support engineer will help troubleshoot the issue.