Nil callback?

[Chizbang]

Hey!
I have a sqlite query function like so:

function getValQ(query, key, callback)
		local done
		local result = MySQLite.query(query, function( data )
			print("test")
			if data then
				for k,v in pairs(data) do
					done = tostring(v[key])
					callback(done)
					print(done)
					PrintTable(data)
				end
				else 
[B][I][U]callback(nil)[/U][/I][/B]

			end
			
		end)

	end

I require to have a call back even though the value is nil on the callback itself. How would I go about doing that?