Photoshop elements 13 on Mac does not recognise my Canon EOS 1000D

I recently changed from a Dell PC running Windows Vista with Photoshop Elements 11 to a Mac running Apple Version 12 with Photoshop 13.  When I connect my Canon EOS 1000D to the Apple Mac using a USB port Photoshop does not recognise that I have a device attached even though the Apple Mac does recognise the fact that the camera is connected to the system. I did not have any problem connecting my camera to my old PC. Is this a problem with the Mac version of Photoshop Elements 13? does any know how I could resolve this problem?