asterisk users - Jul 2005 - Call file ][ Unable to request channel ZAP/g1/0123456789 ][ Call failed to go through, reason 0

Hello,

I have a problem with sending multiple calls from the outgoing call queue.

Everything is going ok, but when I move more then 5 files in the queue the 
following notice messages are shown on the screen:

Jul 13 07:58:32 NOTICE[7597]: channel.c:1817 __ast_request_and_dial: 
Unable to request channel ZAP/g1/0123456789

Jul 13 07:58:32 NOTICE[7597]: pbx_spool.c:232 attempt_thread: Call failed 
to go through, reason 0

We have an Digium ZAP card on a E1 connection.

Paul