There are two control menus for your Titan: the move menu and the attack menu. Both have to have an order before the turn progresses. When you order the Titan to lock on the building, this is an attack menu order. Control then switches to the move menu, which is where you use "Wait... On Call". This gives the move menu an perpetual command; until you specifically call the menu (via the attack menu "Call Move" or the F3 menu), the Titan will not ask for a move command (I think after around 500 secs on a "Wait" command, the Titan prompts for another command, but don't quote me). After the "Wait... On Call", the game proceeds through game secs until the "Lock" command finishes executing, at which point the attack menu prompts for a command. Then things go boom.
As for your problems with the dummy Titan, it sounds like you toggled your scanner off, rather than using Active Scan. There are two buttons on the top row of the attack menu directly related to the scanner. The buton on the left (to the right of the "ECM" button and above the "Wait" button), which looks like 4 expanding curved lines, is the "Toggle Scanner" button. Under most circumstances, this should be blue. Hitting this button will turn the scanner on/off. Except in extreme cases,
do not hit this button. You want your scanner on (blue) 99.95% of the time. The next button to the right, which looks like an "A" with two curved lines above it, is the "Active Scan" button. If you are locked on a Titan within scanner range, this button will be either green or yellow, depending on the range to target (in the Tutorial, it will be green). Hit this button to perform the scan.
It sounds like you put the move menu on "Wait... on Call", turned off the scanner, then put the attack menu on "Wait... on Call". Thus, your Titan did nothing.
Hope that helps. And we won't slap you; we'd rather shoot you.
widowmaker
"The trick is to be angled just right so when your Titan's engine shuts down, you fall behind the cover."
--"Running the Redline", page 37.