cycling through stuff isn't going to get you a "contact".
i'd suggest you post a screenshot if your having anymore issues, but it seems like your missing the radar aspect setting, med, int, hi. so maybe ur radar is in pol mode for aim-7; who knows. but that sounds like ur issue.
so a contact 40nm w/ ecm on, hot.
you would need ur radar set to hi, 80 range 2b, and 20 sweep w/ the correct alt range. point being you want to scan a very small area to find ur target, then expand your search range to see if you can keep it.