Ehh… you are not telling us how you have tried to make the LEDs do what you want to do, so I can not really help you here.
Did you manage to use your LED tube work with other software? You installed the driver from the enttec website? (or the one that came on the CD). You know how to make the LEDs listen to the DMX you send? (Set the DIP-switches to the proper Adress and in DMX mode) etc etc…
The Entec Open is not the Ethernet one, so that was a bit confusing. I really doubt you need a terminator, I never used one in my live, and I make longgggg daisy chains of various DMX fixtures almost on a weekly basis. But than again, this might be the exception.
Like Sunep said, test with a DMX console to see where it all goes wrong.