I doesn't sound like there is an issue with the unit as you have described it. The principle idea of having DI in addition to 2D sonar is to gain a better understanding of the structure/cover you are seeing on the viewer. The position of the structure/cover relative to your boat could be off by as much as 20 feet depending on your setup. For example: GPS in and of itself can be off by 10 feet or so and if you have the GPS puck, or the unit with built in GPS at the console and your transducer sits at the back of a 20 foot boat, you can add another 10 feet. The more you use the HBUnit, the more confident you will be with how far the distance is between to structure/cover and your boat.