WoWInterface - Target Name Not Updating

Hey there, I use oUF_Nivaya along with KGPanels and a few other mods for my personal UI, and the target frames aren't working properly. I didn't really notice it at all until I had to kill something.
What happens is every time I target a Hostile NPC/Player it will show as the last Friendly thing that I had targetted. It will update hp and mana, as far as I can tell, but it shows the friendly green on mana bar [like I have it set to.] and says the friendly targets name. It's really pretty annoying.
Is there a quick fix for it I could do myself, or does anyone know what I could do to make it work properly?

Edit: Screenshot. I am obviously not targeting 'High Chief Stillpine'.
http://i159.photobucket.com/albums/t...009_181724.jpg

This is an error I get once in a while, the first time I target a friendly NPC and then a hostile NPC [Like on TOC 5 man, targetting an argent warhorse, and then an Argent Battleworg] It will say this, update the health, show the green mana bar [for friendly] and still say the "Argent Warhorse" name above the target bar.

Message: ..\AddOns\oUF_Nivaya\oUF_Nivaya.lua line 36:
attempt to call global 'GetDifficultyColor' (a nil value)
Debug:
(tail call): ?
[C]: GetDifficultyColor()
oUF_Nivaya\oUF_Nivaya.lua:36:
oUF_Nivaya\oUF_Nivaya.lua:25
oUF_Nivaya\oUF_Nivaya.lua:83: UNIT_NAME_UPDATE()
oUF_Nivaya\oUF_Nivaya.lua:192: PostUpdateHealth()
oUF\elements\health.lua:98: func()
oUF\ouf.lua:506:
oUF\ouf.lua:501
[C]: Show()
..\FrameXML\SecureStateDriver.lua:72:
..\FrameXML\SecureStateDriver.lua:62
..\FrameXML\SecureStateDriver.lua:111:
..\FrameXML\SecureStateDriver.lua:81

I also posted this on oUF_Nivaya's comment section, hoping to find a fix.