there is an old thread from the Forum and although it relates to Alethzero the Troubleshooting section may offer a few pointers, here is an extract;-
a) I press 'Go' and nothing happens
Before anything else, keep an eye on the log window, look for error messages, but give it time! It take a good 5 minutes from the UPnP connection on my machine to start downloading blocks - and a couple of hours to catch up on the full chain.
If you're not seeing any peers after a few minutes, make sure UPnP is on on your router, and working. Check for UPnP related messages in the AlethZero log window.
If that doesn't help, the bootstrap node is sometimes down, it's expected on a testnet. The simplest way is to press 'Go' anyway (to start the network), then identify a node on https://stats.ethdev.com/ that has plenty of peers (the Go bootnodes are good for this. Click "Network > Connect to Peer" and input the IP of the node and the correct port (30303), as such: xxx:xxx:xxx:xxx:30303.
b) It's 'not working'!
First, upgrade. You might think that that version you installed last night is good enough but it's likely a new one is already out, and very often, the version number will not change after a merge from a debug branch, only the commit hash. So before trying anything else, please go through the 'upgrade' procedure described just above, and try again.
there was a thread about a month ago on OSX build issues
relating to Unable to open Alethone and Alethzero on Mac OSX 10.9.5, a suggested solution was
however the O/P has not reverted.. at this time.