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 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 the Professional Services of your region.
Note: If a Non-Custom App-ID signature is not working as expected, create a Support case and a support engineer will help troubleshoot the issue.