In order to use a Thunderbolt device, you need to ensure your computer has Thunderbolt port. For example, if your Mac or PC is from year 2010, it would not be a Thunderbolt enabled computer. See more information here: Is my computer, display, or cable Thunderbolt capable.
Here are the steps to troubleshoot the Thunderbolt device detection problem:
A. Try a different Thunderbolt cable and try different Thunderbolt ports on your host machine or device – If possible, please try the Apple Thunderbolt Cable. – If your computer has more than 1 Thunderbolt port, please try a different port. Likewise, if your CalDigit device has 2 ports on it, please try a different one.
B. Please make sure your macOS is fully up to date, then verify and repair your macOS permission. When finished, please reset your PRAM and SMC 3 times in a row. (http://support.apple.com/kb/HT1379) – If you are running the 10.8, please make sure to download the “OSX 10.8.5 combo update” and “OSX 10.8.5 supplement update”, same goes for the “OSX 10.7.5 combo update” – Make sure all EFI and SMC firmware updates are applied.
C. Power ON – Our Thunderbolt devices need to connect to a running computer with the Thunderbolt port. – If your computer is NOT on, the Thunderbolt device will not run. – If the Thunderbolt device is not connected, it will not run either. – The best method is: power ON your computer first, then connect Thunderbolt device to your computer. After that, please turn ON the Thunderbolt device if there is a power switch on it.
D. Try to move the Thunderbolt device into the front of a Thunderbolt chain. – If you are daisy chaining the new Thunderbolt device, please try moving it as the first Thunderbolt device in the chain to test run it. – Try a different wall mount or outlet for the Thunderbolt device AC adapter as well.