More sonar questions

[nutworld]

I'm still working on my sonar skills, this time using Bill Nichols "VENGANCE" scenario, where my 688 has to locate, identify and kill a Kilo.

My question is this: Don't contacts in the NB display that look something like this ___^___ signify a contact at that designated bearing? (please forgive my "graphic")

When playing this scenario I hear the surface contacts that "seem" to be surface squall, and those lines appear solid on my waterfall display in the BB waterfall.

When I click on the designated bearing that I show above, my NB waterfall display shows no contact lines.

I'm not looking for cheats or things like that but I just don't understand why my NB display would show what "seems" to be a strong contact, showing nothing on the waterfall.

Thanks for your help.