reverse not engaging

I have a 90hp four stroke outboard and put it in the water for the first time this year and it will not engage into reverse. All I get is a spinning noise like the gears and missing each other or grinding. Anyone have any ideas as it sat in the garage over the winter and had no problems last year?

[jb123]

unhook gear shift cable at motor, run on hose and manually shift motor shifter....if it goes in and out of gear your cable needs adjusting...if NOT then your lower unit and/or shift shaft needs work.