DialPlan hanging sometimes when using System()

I am using Asterisk 1.6 and trigger allcalls using callfiles by copying them to a temp dir and then moving them to Asterisk’s ingest dir

; ALLCALL
exten => 1211,1,system(cp /AllCall/.call /tmp/callfiles/)
same => n,system(mv /tmp/callfiles/
.call /var/spool/asterisk/outgoing/)

Testing showed that sometimes the second priority did not run so I added a NoOp and even a wait between the copy and the move yet the problem still occurs - but only sometimes.

So if I run the extension below, and look at Cli, it will run completely 75% of the time but about 25% of the time it will end at wait(1.5) without any error so it does not do the move

Any ideas why and what I can to do troubleshoot?

Thanks
Bill

; ALLCALL
exten => 1211,1,system(cp /AllCall/.call /tmp/callfiles/)
same => n, Wait(1.5)
same => n,system(mv /tmp/callfiles/
.call /var/spool/asterisk/outgoing/)