I have a new Helix 7 SI/GPS. Today is the 4th time I have had it out on the water. I can not get anything but a black screen with SI and DI. I have tried using all the frequency choices and have no luck. My sonar view is questionable but I have at least gotten it to function. Does anyone have any suggestions for any thing I might be doing wrong? My transducer mount is good from the info I have looked at online so I don't think that is the problem.