I would suggest that you follow our POD Studio setup video tutorial to assist you with getting started with your Line 6 Audio interface:

http://line6.com/support/docs/DOC-2499

You can watch the video and use the download links below to get the latest software to go with your POD Studio. First make sure to download and install the latest Line 6 drivers for your operating system:

MAC Drivers : 7.1.3

http://line6.com/software/readeula.html?rid=4321

Once the drivers are installed you will need to install the Line 6 Monkey application from the links below:

MAC Line 6 Monkey 1.51:

http://line6.com/getrelease?rid=4619

Once Line 6 Monkey is installed, remove any additional unnecessary USB and firmware devices from your computer when troubleshooting this issue. Make sure to connect it directly to a USB port and not a USB hub, extension, or keyboard of any kind, preferably connect it to a USB port on the rear of computer. Try using additional USB cables and every USB port available until you are able to launch Line 6 Monkey and detect the device.

After Launching Line 6 Monkey apply any updates that are available until you have a green check next to each component.

Next close all open applications and use the License Manager software to de-authorize and re-authorize your device. Make sure to remove the information when prompted to, and then install again when prompted to, this will ensure that you reinstall all of your available Line 6 assets from your account into your device.