Elliptical trouble

So I’ve joined the gym and I’m loving it. I just can’t seem to get over knee pain when I’m using the elliptical. My knees feel like they are going to fall off in just a couple of minutes of use. Does anyone have any tips or exercises to help me strengthen my knees? I can walk on the treadmill and do the stair climber with no problems so this is baffling to me.