MixMonitor inconsistantly saving files

Asterisk Asterisk Support
1

At the moment MixMonitor isn’t consistently saving audio files, and i cannot for the life of me figure out why. This is a snippit of a case where a file DIDN’T get saved, MixMonitor is ending and closing the recording like normal.

  == Using SIP RTP TOS bits 184
  == Using SIP RTP CoS mark 5
    -- Executing [0466621277@from-internal:1] MixMonitor("SIP/7104-000d493f", "1340953097.873138-out.wav,b") in new stack
    -- Executing [0466621277@from-internal:2] NoOp("SIP/7104-000d493f", "Call from "Joe" <61399127104>") in new stack
  == Begin MixMonitor Recording SIP/7104-000d493f
    -- Executing [0466621277@from-internal:3] AGI("SIP/7104-000d493f", "api-mysql-outbound.php,0466621277,Joe,20") in new stack
    -- Executing [0466621277@from-internal:4] Dial("SIP/7104-000d493f", "SIP/CL/61466621277,45") in new stack
  == Using SIP RTP TOS bits 184
  == Using SIP RTP CoS mark 5
    -- Called SIP/CL/61466621277
  == Spawn extension (from-internal, 0466621277, 4) exited non-zero on 'SIP/7104-000d493f'
  == End MixMonitor Recording SIP/7104-000d493f
  == Spawn extension (from-internal-default, 0404566285, 4) exited non-zero on 'SIP/1100-000d4922'
  == MixMonitor close filestream

What could be wrong? Where should I look for issues?