Is there a possibility the wire adapter you bought is damaged or otherwise incorrect?
Some third party brands may or may not provide proper connections. Have you tried
another adapter to see if that is the problem? Also inspect the port in the computer.
• Apple Thunderbolt cables and adapters - Apple Support
If you still have issues, contact the authorized reseller or an Apple Store about this
situation because the computer is under warranty if the port is somehow defective.
{Also, the use of a secondary adapter may be needed to use FW400 products.}
• Apple Thunderbolt to FireWire adapter -- Apple Store:
http://www.apple.com/shop/product/MD464LL/A/apple-thunderbolt-to-firewire-adapte r
Also, if the adapters do fit correctly, but the products don't work -- and a second adapter
does the same thing even though it tested OK on a different Mac -- you could try to see
if an SMC reset could help the computer recognize the ports and peripherals attached.
• Thunderbolt ports and displays: Frequently asked questions (FAQ) - Apple Support
Sometimes, the SMC reset may or may not be helpful. Or the situation may require an
other kind of reset known as NVRAM. -- However the adapter may be defective; or not
correct. The older Mini DisplayPort adapters can be confused with ones intended for
use with Thunderbolt; some won't work.
• Resetting the System Management Controller (SMC) on your Mac - Apple Support
• How to Reset NVRAM on your Mac - Apple Support
Good luck in this matter! 🙂