Auto-dial out - making an outgoing call

When i try to make an outgoing call with the auto dial functionality the following message pops.

WARNING[30591]: cdr.c:509 ast_cdr_disposition: Cause not handled

NOTICE[30591]: pbx_spool.c:341 attempt_thread: Call failed to go
through, reason 8

can any one tell me what might be the mistake with my configuration setup.