G-Raid with Thunderbolt 2 not recognized on MacBook Pro

I have a MacBook Pro 2015 running OS X El Capitan. My computer does not recognize the G-Drive w/ Thunderbolt 2 when I use the Thunderbolt 2 cable supplied. It does recognize the drive when I use the USB cable. I was able to initialize the drives and set them up as JBOD but I want to use the TB2 cable not the USB. I also don’t want to purchase a new TB2 cable at $40 if this is not the problem. (I have a monitor that uses TB2 connection and it works in both of my ports so question the cable.)
Suggestions?

Make sure the connection you’re plugging into is actually Thunderbolt. It will have a lightning bolt next to it. It is likely you are plugging into a mini display port which is only for display.

Also, the speed would be the same over USB 3.0 or TB2 with this drive.

Rydia, thank you for the response. My MacBook Pro has 2 thunderbolt ports,
both have the lightning bolt next to them. I do not mind using the USB but
it is a new drive and I would expect all the ports to work properly.
Suggestions?