connecting a USBc (USB3.1gen 1) DEVICE... to a Mac Pro ("trash can" Mac) which is Thunderbolt 2

I have purchased the Apple Thunderbolt 3 to Thunderbolt 2 adapter. (they say that should work both directions (unlike most adapter)

so again it's a Late 2013 12 core Mac Pro that I'm trying to connect a USBc / Thunderbolt 3 dock that holds a 1 TB SSD eSATA drive) using a 1.5 m Thunderbolt 2 cable to an Apple Tuinderbolt 3 to thunderbolt 2 adapter not working anyone know why it's not?

thanks, brad b Studio51

Belkin Thunderbolt 3 Cable

Belkin Thunderbolt 3 Cable

Product No Longer Available

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