My BC350A scanner does not stop on active frequencies when its on scanning mode. I got to operate it manually. The squelch is at 12 o'clock. Does anyone know what the symptoms might be ?
This may seem obvious, but just to rule it out as the potential problem; Is the bank that contains the channel you wish to hear enabled?
Have you tried it with a lower squelch setting than 12 o'clock? At the 12 o'clock (or higher) setting, the scanner will pass over weaker (but still active) channels that are loud/clear enough to hear, but not quite strong enough to break the squelch.
Although squelch control often varies between scanner models, the general rule of thumb (if you're trying to hear as much as possible) is to turn the squelch down all the way and then slowly turn it back up just enough so you don't hear the static anymore. This will keep the scanner from skipping channels that aren't strong enough to break the higher squelch setting.
Good Luck
