I noticed you haven't recieved a response to your question yet. If you could provide the following information, it may help others in the Apple Support Communities get you to a solution:
- What is the exact message you are receiving?
- What are you doing with the devices -- are you using the Personal Hotspot from your iPhone to get online with your iPad, for example?
- What are the iOS versions currently running on your iPad and iPhone (you can find this under Settings > General > About > Version on both devices).