CONTROL Key Bounce Question (Formerly ALT Key)

Hi.
 
X3 Studio User.
 
When I want to select tracks for bouncing I have been using the CONTROL key by selecting one channel, holding the CONTROL key and going down and selecting all the rest of the tracks I want to bounce.  They should all stay "lit" but that doesn't always happen.  What frequently happens is say, I want to bounce tracks 5 & 6 together.  I'll click the button for track 5, hold down the CONTROL key and then click track 6.  Both tracks should light up, but they frequently don't.  When I go to 6 it will light up but 5 will go out, and back and forth.  I have to play with them and coax them until I get lucky and both will finally stay lit.  The same happens when I want to bounce clips.  Sometimes it's a challenge to get all the clips to light up so I can bounce them together.  Am I just doing something wrong?
 
Thanks so much in advance.
 
John B.

You know what?  I stand corrected.  It IS the CONTROL key I always use, so on my initial post (and the title) I (edited) changed the ALT key to the Control key.  I do still have issues this way.  My bad.  Sorry.
 
Again, any help would be appreciated.
 
John B.

tenfoot
Are you selecting the tracks using the track numbers John?
 

Yes.  Clicking on the numbers.  Holding the CONTROL key.  Funny, but when I want to bounce all of the tracks to render the whole mix, I click on one of the track numbers, then the CONTROL + A and they all highlight.  But not if I want to only choose two or three.  And, as I said earlier, this happens on the clips too sometimes.