Forced Navigation

I've read everyone else's solutions and just wanted to throw another possible approach solution in the mix.  Create 3 variables box1,box2, and box3 and set all three values to zero

On the 'Enter Frame' execute javascript and create the following function:

function checkBoxes(){

if (box1==1 && box2==1 && box3==1){

cp.show('nextBtn');

}

}

For each box button execute this javascript (change the box number for the different boxes - i.e. box2 = 1, box3 = 1)

box1 = 1;

checkBoxes();

This way you don't have to create three different advanced actions.  

Ah ha!  I had no idea that was how you used the "untitled tabs"!

Here is an idea.

Start with next button hidden.

What if you then have a variable for each text box where a value of 0=not visible and a value of 1=visible.

Initial value is hidden or var_xxx = 0 When the user clicks on the box we not only show the text but assign the variable with 1

You could then have an action where IF var_box1 = 1 and IF var_box2 = 1, and IF var_box3 = 1 THEN show "Next"

You need a user variable for each interactive object to be clicked. I will label them v_one, v_two and v_trhee. Set their default value to 0, they will be Booleab.

I cannot post screenshots because I don't know which version you use. For each interactive object you'll have to create an advanced action with 2 decisions:

First decision 'Always'  has to be a standard action

     Assign v_one with 1

Second decision 'ShowNext' is conditional:

     IF v_one is equal to 1  AND

          v_two is equal to 1  AND

         v_three is equal to 1

    Show Bt_Next