I had a simple animation (student project) which was working fine. I decided I would slow it down a bit, as follows: in Dope Sheet, select all, Scale, then drag the whole shebang R to start on Frame 0 as before. Used to be 170 frames long, now 270. Preview is fine. All seemed well.
Then I rendered it. The rendered version stops (black screen) after frame 170, "remembering" the old length. Yes, I did remember to set Begin and End frames in the Animation parameters :-) They are set to 1 and 270. If I step through in Preview, rendering individual frames, I can see that frame 170 is normal and frame 171 is black-screen as are all subsequent.
There must be some other place -- other than the Timeline and the Animation panel -- where length of animation is set, but I can't find it. Can anyone clue me in?