Pull tray completely out. There is a knob that directs water into the tray. It is straight back in the top of the cavity. If it is not there it may have fallen out. If this happened ...you will find that little sprayer know in the bottom of the cavity. Mine fell out and I put it back in by wiggling it and pushing gently up into the spout...and it fell out again. You may want to use a small mirror and a flashlight to see what this looks like.
I am looking for that part now.