Have a look at this article about the two-step design of the default quiz slides:
Question Question Slides in Captivate - Captivate blog
It looks like you are still on a version before 9, since you talk about a Next button. In CP9 it is a Skip button, which was also its meaning when it was labeled Next in previous versions.
The reason for the two-step design is this:
- Click Submit and the feedback message (Success, Last Attempt or Retry) appears; the playhead is not moving but remains at the pausing point (default 1,5secs). For Retyr, user can change or edit question and submit again.
- In case of Success/Last Attempt user can read the message and has to click on the slide or press Y to get to the second step
- Second step: playhead is released and the actions specified for Success/Last Attempt are done
If you don't want a message to appear, you'll find a tweak in my article. After reading this expanation, what do you really want to happen.?