Volvo won't shift

[scooter808]

I have a Volvo 4.3 with a Penta drive, when I start the boat the warning buzzer won't stop and I can't shift into forward or reverse. Also, with the motor off it still won't shift. I looked over everything, (didn't have tools to tear everything apart) and I didn't see anything out of the ordinary. Any ideas as to why it won't shift. Thanks in advance.