I'm also having that bug GSarahC. Every enemy plane that starts on the right side of the screen took a point off my # and the whole campain was lost. Others have been talking about this also. Please look into it.
You should not be able to try to train when there are the max number on the field. The buttons should be greyed out or something. At least tell us how many we have on field.
I have 4 locks with actual #s next to the, no zeros, do I just keep killing enemies until I can use them? I can't stop playing this game even though I barley know what's going on.