Next button not returning to normal

Greetings:

Could someone please help me? I've tried everything I can think of, but nothing is working. This needs to be resolved really soon!

I want the following to happen:

1. Learner must click all of buttons before they're able to click the next button to advance to the next slide. This is not happening, as the next button never changes to normal state! 

What I did:

1. I changed the player settings where the navigation is restricted so that the next button is automatically disabled until the timeline ends. (I think this is what is supposed to happen!)
2. I disabled the the next button when the timeline starts and the added variables so that when the variables changed to true the next button would change state to normal when the timeline ends if all of the chosen variables were true.
3. I disabled the the next button when the timeline starts and then added conditional triggers so that the next button changes to normal when the timeline ends if all buttons are in visited state. 

What kind of help I need:

1. All I want is for the the learner to have to click on all of the buttons and be able to go to the next slide, but the next button never changes state to normal so they can't click it to go to the next slide. 

I have attached the file to this post. Thank you so much for your time!

Best.

Ashley