Survival is the phase when your team has lost all its lives and the timer starts to run, if you never reach that stage (because you didn't loose all you lives) you will not be credited for that stage, it's a bit wierd, but that's how it works I think!? It should be the other way around, getting credited for not reaching this stage, right!?
It's the same wierd thing like having to play multiplayer games to unlock the training mode, very strange decisions?