These were all useless answers... especially the one from PBK saying that the message tells you all you need to know. It VERY obviously doesn't if this question has been viewed 26,000 times! The solution is quite simple actually. Go into your iPhone (or other device) settings. Scroll down to Privacy and Security and enable Developer Mode. Reboot, follow the prompts to enable it (you may have to reboot your iPhone and your Mac once more if the versions are out of sync) and Bob's your uncle.