GMC Sierra reverse light problem

Hello I have a 2002 gmc sierra 4wd 1500 series 4.3l. I just replaced the transmission on it along with the neutral safety switch. The problem I am having is the reverse lights come on when the truck is in park and turn off when it is placed in any other gear. I have switched around the green wires on the neutral safety switch and that has not helped. Do you have a schematic I can take a look at or do you know what the problem might be.
Thank you,
Eric