Zygo is right, it could be that simple.
If you think of it all as a huge CB radio, you could be talking to them on one channel but they could be tuned in and listening on another one. You both have a radio, but you will not communicate until you find the right channel.
Try giving out your energy on a different frequency, and try using feelings rather than words. This will make it easier for the message to get through. Once the first contact is made then you can start trying to use language to communicate with them.
If it is easier try seeing your channels as different colours, that should be easier for you if you see auras, as they are always coloured to the different energy vibrations, and send out your message on different colour bands until you find the one they are listening to. They are out there somewhere you know that because you can hear them, but the problem comes because I think although you are hearing them by tuning into them on their natural channel, you are trying to speak to them by sending your message out on your natural channel.
What you have to do is listen for them, and when you next hear them try and reply to them on the channel you are listening to, not the one you would normally use to transmit.
It isn't always easy to change your transmitting channel but it can be done, so keep trying and I hope we have helped you.

Lady C.