Metatables and pcall?

I'm trying to understand how metatables work and this is my first time trying to use pcall .

local tabl = {pig=15,foo=25}
local mt = {
    __index = function(self, key)
        error(key.." doesn't exist in this table")
    end,
    __newindex = function(self,key,value)
        error("You can't make a new value for this table")
    end
}
setmetatable(tabl,mt)

local success, message = pcall(print(tabl.piggy))
if success then print(message) end

I'm not really sure why the last 2 lines don't work, instead it actually errors and stops the script. Im either using pcall wrong or it just doesn't work for errors inside metamethods? It was based on this:

function BadPrint()
    ppppprint("Hi Mom!") -- This will error.
end

success, message = pcall(BadPrint)
if success then
    -- Stuff
else 
    print("An error occurred: "..message)
end

EDIT: I just realised that i was checking if it's succesfull. (genius) I changed that but it still does the same thing since it never actually gets to check..