GetAddOnMetadata function

[Seerah]

Okay, so I'm writing my first addon - thought I'd start simple, since I'm learning pretty much everything as I go. All it will do is pop up a frame when a new version of that addon is installed. I made my frame in WoWUIDesigner, wrote out my lua page, and thought I'd store the version number in saved variables. Then, if the new version number is > than the saved version number, the frame would pop up with the major changes in my UI comp - things that users might need to do, like reset databases, etc. Because, let's face it, not everyone reads changelogs. (There would be an option to disable, of course.)

So... I found this function on WoWWiki - GetAddOnMetadata("addon", "field"), but I'm having difficulties in putting it into practice. Any help would be greatly appreciated.

Here is my lua:

--variables
SSWELCOME_LASTVERSION = 0
SSWELCOME_VERSION = 0;

function SSWelcome_OnLoad(self)
    self:RegisterEvent("ADDON_LOADED");
    self:RegisterEvent("PLAYER_ENTERING_WORLD");	
end

function SSWelcome_OnEvent(self, event, ...)
    if ( event == "ADDON_LOADED" ) then
		local addon = select(1, ...);
		if ( addon == "SSWelcome" ) then
			DEFAULT_CHAT_FRAME:AddMessage("Welcome to Seerah's Suitcase!");
		end
		return;
	end
    --current version?
	if ( event == "PLAYER_ENTERING_WORLD" ) then
		SSWELCOME_VERSION = GetAddOnMetadata("SSWelcome", "Version");
        return;
    end
    --updated?
    local version = GetAddOnMetadata("SSWelcome", "Version");
	if ( version > SSWELCOME_LASTVERSION ) then
            self.frame:Show()
        else self.frame:Hide()
    end
    --update sv
        SSWELCOME_LASTVERSION = version
end

and this is what gets put into my saved variables file....

SSWelcome = nil