Adding Conferences

I added some Conference DN’s, the users inside the office can access them, but when an outside caller comes in through the IVR and dials the 4 digit DN of the conference, they hear the message “we have not received a valid response”. I suspect I have missed a step here, can anyone tell me where I should look? It appears the IVR does not like the DN that was dialed, so do I need to program the DN’s somewhere in the IVR??
Thanks
Al

The direct dial feature is for extensions. You have to set each conference as a destination in the IVR