new lg4000 antenna accuracy problems

Hey guys I just installed a new hds 10 with the lg 4000 hooked to the nmea 2000 network. From looking through previous post other people have had the same problem I have. If I mark a waypoint while on the structure scan screen and try to come back to it I cannot find it. I am marking a brush pile that I have been fishing for a long time so I no its there. It just seems that the gps is way off. My antenna is mounted at the back of the boat on top of the transom directly above the transducer. My unit is setup to use that antenna not the internal one. Did anyone come up with a fix or suggestions?

Are you sure your NMEA2000 network is working? Check your data sources at the Unit you are marking waypoints. If the head unit is not detecting the LCG4000, you could be boat length + EPE distance in error depending where your head unit is mounted.

Mine works fine.

Cane pole, when I go into the menu where I can choose the internal or the external gps would the lg 4000 show up in the menu if it was not working. How is the best way to check to see if it is working? If I select the lg4000 I get reception but it may be defaulting back the units antenna.

Zoom in all the way.
Be sure the orange square is around the map

If you mean when I am approaching my waypoint I have been zooming in all the way still no luck.

Check to see if the lcg4000 appears in the data source. got to menu, highlight Network, enter, scroll to data sources, enter, highlight GPS, enter, highlight all data, enter, LCG4000 should appear here and have a blue dot on.

If you do not see lcg4000 here, it ain't working.