If the fax is a rather large fax with large files be sure that it isn't hitting the maximum amount (The maximum amount for outbound fax is 250 pages or 64mb whichever comes first).
If it is a very large fax I suggest splitting it up in to 2-3 faxes and stating on the cover sheet to the receiving end "FAX 1/3" for example to notify them to expect a second fax.
If this does not help the issue, please send a helpdesk ticket to us here at Procentive.
Customer Care and Training Specialist.
Thanks for the comment, Amanda. It is not a large file, but that's good to know for the future. I tried another record as well, and I had the same problem.
I did submit a helpdesk ticket, so hopefully we'll figure it out.
Customer support service by UserEcho