Did you take the unit off of DEMO mode?
Just kidding.
Well,
Make sure there is nothing interfering with the transducer .
It needs a clear path to shoot out to each side.
You may need to trim up your motor to create a clear path.
Maybe if the transducer is installed too low or too high on your transom, it
could be getting too many air bubbles from turbulant water. You could try moving the transducer to another location.
Make sure the transducer is more or less level when your boat is in the water.
It could be pointed too far up or down. I think the optimum is pointed slightly downward.
Make sure the transducer is clean.
I'm all out of ideas.
Good Luck.