DTMF / Call Parking and Transferring issues

We are running Asterisk 1.4.4 with snom320 phones. When calls come in, we are sometimes able to park calls using #9, and sometimes it doesn’t work. (Completely random). We have set the DTMF mode to rfc2833 on our phones. Also, once we pick up a call from being parked, the #9 shortcut to re-park the call never works, and the ## to blind transfer works sometimes. I have tried both in-band and rfc2833 for our dtmf modes. Help!

features.conf:

[featuremap] blindxfer => ## atxfer => *7 automon => *1 parkcall => #9 disconnect => *0

extensions.conf:

[incoming] exten => s,1,Dial(${HUNT1},20,tkw) exten => s,2,Goto(mainmenu,s,1)