We were having problems with getting Ratio or Adaptive dialing to work. The system would dial out but would never connect the call to an agent. We found out that the Queue Metrics Logging was enabled and when we turned that off, cause we are no longer using Queuemetrics, the system started connecting calls to the agent.
I've seen several posts about users having issues with ratio and adaptive dialing. So if you are having this issue, this is an easy first troubleshooting step.