Hi, ynsaen is correct , you cannot delete frames in the middle of an animation. You need to delete any keyframes and move the frames from the break to the end of the animation. e.g you want to remove frames 20-29 in a 50 frame animation.. select frames 20-29 and press delete keyframe. then select frames 30-50 and move them to frames 20-40. you now have a 40 frame animation. If you want to get rid of one frame - delete it as a keyframe if some action at that point is incorrect or forget it. One frame at anything over 24 frames per second is not visible. if you want to keep the deleted frames for later use do this. example. set animation to frames 0 - 100 set the frame range to 0 - 50 move the frames to be deleted to say 80-100 they will not appear in the render because they are out of range. If you do this be aware the spline interpolation will take these frames into account. either use the straight line interpolation from the end of your animation or put in a break. hope this helps, and is understandable. regards