Why is my Newly replaced screen changes color?

Hey ifixit members. I replaced my iPhone 4S recently with a zeetron screen and everything went well. I followed the guide and everything is assembled. However everytime I press on the corner of the screen it changes color. Kinda like when you press on a calculator screen it changes color. After a few seconds it goes back to normal. Is there too much stuff under the screen? There was this plastic that I took off from the back of the new screen and I left the second silver plastic since the original screen had the same silver plastic. Is this what's causing the problem? Or is there like an adhesive that I need to use when installing the new screen? Any help is Appreciated. Thanks

-Hunter