[Fizzlemizz]

I don't know BigWigs but that code tells me it is marked as Load On Demand (LOD).

If you open it's .TOC file you should see and entry:

## LoadOnDemand: 1

This means the addon (and it's frames) are not loaded/created until the addon is specifically loaded during play (probably by entering a dungeon or raid).

You have two choices,

1. Wait for an "ADDON_LOADED" event where the first payload parameter (the addons name for this event) is "BigWigs" and then do what you need to do,

2. Test if the addon is loaded and if not, load it yourself using

if not IsAddOnLoaded("BigWigs")
      local Loaded, Reason = LoadAddOn("BigWigs")
      if Loaded then
           -- do what you need to do
      else
            -- it didn't load for Reason
      end
end

I would suggest using the first if possible unless there is some specific reason you need the BigWigs frames earlier.