I enable threat color, but off-tack color is wrong.

You mean that the healthbar is not colored correctly wihth the offtank color? There could be two reasons for this:

1. There is an error with selecting the correct color. For this, which color is used for the offtank?
2. The currently targeting unit is not considered a tank which means that it's shown like a dps taking aggro from you. On what version of WoW is this happening?

There is indeed an error with role detection in raids/groups - at list in Retails and possible Mists. I am not sure if this is also causing your error, but I will fix this error and then we'll see.

I uploaded a new version where tank / offtank detection based on your role in raid is fixed (in Retail at least).

thanks.

If it still does not work for you, please comment here again.