GetMapNameByID a nil value?

[eoblaed]

Fixing up some of the addons I use in the face of today's pre-patch release. So far, I'm batting a thousand, but coming across this error:

attempt to call global 'GetMapNameByID' (a nil value)

is a little problematic. I've looked up this API call here and it doesn't indicate it's moved 'tables' (like SendAddonMessage did).

Here's the top of the .lua file in question:

local addonName = ...
local addon = _G[addonName]
local colors = addon.Colors

local L = LibStub("AceLocale-3.0"):GetLocale(addonName)
local BB = LibStub("LibBabble-Boss-3.0"):GetLookupTable()
local LCI = LibStub("LibCraftInfo-1.0")
local LCL = LibStub("LibCraftLevels-1.0")
local TS = addon.TradeSkills.Names

local SilMapName = GetMapNameByID(261)

Is there something else this file needs to allow it to get visibility of GetMapNameByID? (eg. in the C world, a #include, etc).

Thanks!