Dial plan execution does not fall back to next trunk in trunk sequence

Hi All:

I am running FreePBX 2.4.0. I have couple of trunks setup: one is a SIP trunk and second one is a ZAP trunk. For my long distance calling I have chosen my SIP trunk as trunk 0 in the trunk sequence and ZAP trunk as trunk 1. But when calls to SIP trunk fail (time out after 5 minutes) the execution doesn’t automatically go to next trunk which is the ZAP trunk. It use to work in earlier FreePBX releases.

Any idea what might be wrong here?