Tar Ant Task problem

I was using Tar task in one of my build scripts and ran into this error:

[tar] Nothing to do: XXX_XXX_1_0_0.tar is up to date.

This was weird because I got this error when I ran the script for the very first time. It turned out that I had the wrong entry for the "includes" attribute and so bascially tar couldnt find anything to tar up. Talk about misleading error messages!