Tranny/shifting question on 2010 Rancher AT

I have a 2010 Rancher AT w/ power steering. I noticed that while on the trails that sometimes when I have to go into reverse or from reverse back into drive. This mostly happens when trying to go into reverse it seems. When I push that red pin in and pull the handle and then push the shift button down to put it into reverse. I will hear and feel the transmission try to shift into reverse but as soon as it feels like it is changing gears it goes right back to neutral. I see the Icon on the Screen show the Reverse symbol for a second and then it goes back to Neutral. It will sometimes do it 2 or 3 times in a row before actually going into reverse. It has happened going into drive as well but not nearly as often. Am I doing something wrong? When I do this I am just pushing the button in and letting it go. Should I try and hold the button down longer or something?