WowAce

What steps will reproduce the problem?
1.When Item compare for Druid class.Other class is No Problem

BugSack UI error log

12x RatingBuster\RatingBuster-5.0.4.357.lua:3389: attempt to compare number with nil
RatingBuster\RatingBuster-5.0.4.357.lua:3389: in function "func"
RatingBuster\RatingBuster-5.0.4.357.lua:4393: in function "StatSummary"
RatingBuster\RatingBuster-5.0.4.357.lua:2727: in function "handler"
libs\LibTipHooker-1.1\LibTipHooker-1.1-16.lua:179: in function <libs\LibTipHooker-1.1\LibTipHooker-1.1.lua:174>
<in C code>
<in C code>
FrameXML\ContainerFrame.lua:815: in function "ContainerFrameItemButton_OnEnter"
<string>:"*:OnEnter":1: in function <string>:"*:OnEnter":1