I think it would help u to have the 2d view showing also.by having di/si and 2d all showing at the same time,u can compare what being displayed.
From looking at the picture that u posted,the unit appears to be working,but there's really no way to no for sure from looking at the picture.
I think that u should restore defaults first.choose the three way view (si/di and 2d)find some kind of known structure to scan and only adjust the sensitivity as needed.nothing else.do this until u get a better feel for what the unit can do and display.Go over the structure at different speeds and try different directions to. (Please send us some more picture also.u will get lots of help here)