Adapter Engine message Status: To Be Delivered?

I have SAP outbound idocs that have suuccessfully been RFCd and successfully receieved in XI (checkered flags in SXMB_MONI). However, they are not being placed on the designated server. In the message monitoring, under the adapter engine we get the message "To be delivered". We do not get any other message that will tell us the problem.....The queues are not jammed up.

Can anyone please tell me what may be going on?

Thank-You.