After installing RatingBuster r200 and AuctionLite 0.5-beta I got this error message and RatingBuster stopped working:

RatingBuster-1.4.1 (r200)\\RatingBuster.lua:3356 attempt to perform arithmetic on a nil value
RatingBuster-1.4.1 (r200)\\RatingBuster.lua:3788 in function `StatSummary'
RatingBuster-1.4.1 (r200)\\RatingBuster.lua:2171 in function `handler'
LibTipHooker-1.1-2:193: in function <...ingBuster\\libs\\LibTipHooker-1.1\\LibTipHooker-1.1.lua:187
<in C code>: in function `SetLootItem'
Interface\\FrameXML\\LootFrame.lua:198 in function `LootItem_OnEnter':
<string>:\"*:OnEnter\":1: in function <[string \"*:OnEnter\"]:1>

Any hoverlink or comparing tooltip gave a similar error; reverting AuctionLite to version r37 solved the problem. (I'll post this ticket to the AuctionLite page too.)