Lightbox images are all black and white

For a while now I've been working on a rather simple website for myself. I wanted to add a Lightbox since I thought it would suit the design, but I made a mistake in the process. Since I chose to use black and white images I decided to use the grayscale function. Now all the Images that I view with my Lightbox are black and white.

This is the Lightbox I use http://ift.tt/R48r69



This is a small but very important piece of my htmlhttp://ift.tt/1vTSEkF

can anybody tell me what I did wrong

Thank you in advance