OK. That red line indicates a Full Motion Recording of your scrolling action. FMR is like a video file and usually gets converted to video at publish.
For some reason it appears that your slide 28 is fouling up the publish.
Try hiding slide 28 and then publishing. If that works, unhide the slide and try again. If it still trips up, try editing the slide FMR slightly. Perhaps chop out a few frames at the start or finish to see if editing fixes something.
Worst case scenario, you'll need to capture that scroll motion again, or do without it by just including a few separate captures of you clicking the scroll bar instead of dragging it. I know that won't look as nice, but in a pinch it will usually suffice to show the concept of scrolling down the page.
Thank you, I have hid the slide and it successfully published. I then showed the slide again and it published. Strange!
with regards to the FMR file, the edit button is greyed out in Captivate, if I go find the source file, I can only launch it in the browser.
Thank you for helping, the hide/unhide did the trick!