The effect looks great there, bill. I would suggest that the reason people arent' completely convinced by it is that it's not a great tattoo in and of itself - which is not your fault, since you were just using a simple image as a demonstration. 

I do wonder if the specular is a little high on the finished result - it reminds me more of those kiddie tattoos that you put on with water, rather than the 'proper' adult ones. Still, that could just be personal taste. Great work on working this one out for us!

JonTheCelt