addon incompatible

[programdat]

I am trying to write a simple hello world program just to get myself started writing addons. I have created the needed files and it is showing up in the addons menu in wow. However next to my addon in red writing it shows "incompatible". Any help would be greatly appreciated.

Here is the code in my TOC

##Interface:50400
##Title:Hello, World!
##Author:Me
##Version:v1.0.0
HelloWorld.lua
HelloWorld.xml