Render Movie - Sequencer loses control of camera

I have a camera movement that plays back perfectly in Sequencer. But when I render it out as a png sequence the first few seconds are OK, but then it’s as if control of the camera moves from the sequencer to my mouse! (If I move the mouse around the camera swivels accordingly.)

Any ideas gratefully received. Thanks.

I found the problem (Duh) I needed to grab the edge of the clip icon in the Camera Cuts track and drag it out to the full length of the sequence.