[Dridzt]

Originally Posted by Zax Thanks Keeping in mind what you said, I tried this: But it doesn't work (my personal echo() function just displays a text in the chat box): the TEST message in well displayed but the guild frame is not shown. I suppose it is because this script is called on VARIABLES_LOADED event. I was just trying to display guild frame when entering WoW in order to quickly see the connected guildmates.

Yes your guess is correct, VARIABLES_LOADED is too early.
Also LoadAddOn() is not good practice, it can break other LoD Blizzard addons, most notably the Calendar.
This might be better:

local f = CreateFrame("Frame")
f:SetScript("OnEvent", 
function(self,event,...) 
    if self[event] then 
        self[event](...)
    end
end)
f:RegisterEvent("ADDON_LOADED")
function f.ADDON_LOADED(...)
    local addon = ...
    if addon == "Blizzard_GuildUI" then
        ToggleGuildFrame()
    end
end