Mandatory Entry Boxes

That's why I was asking. Your work around is actually a proper use of the TEB feature in Captivate. You have learned that you can validate the response in the set up of the TEB to evaluate the learner response. You can have a single valid word or phrase or a number of them that you set in the Correct Entries. The TEB is an interactive object that by default pauses the timeline. Once the learner has entered the correct response the timeline continues to play (the default success action) which is set to Continue. If they put in the the wrong answer and if the number of attempts is set to Infinite Attempts, the learner is more or less stuck in a loop and will have to put in a correct response before the learner will continue. So when you removed the back and forward arrows from the skin, you used the timeline control features of the TEB .You also have learned that the TEB can provide learner feedback by setting the Display for the Success and Failure Caption based on the learner response. 

Your Text Entry Box is already tied to a variable. By default, it will be something like this  Text_Entry_Box_1

Have a Submit button that when the user clicks, it will perform an advanced action.

If you want them to type a specific thing, say - the word dog - then the action will be something along the lines of

If Text_Entry_Box_1 = dog

then show  next button

You might also have it simply go to the next slide.