How do I have the learner perform a conditional action based on a button selection?

Question

The learner needs to select a checkbox on the screen of a performance exercise.  I've put the widget in for the checkbox and it works fine.  After the select the checkbox, they need to select OK on the screen to move them onto the next screen.  However, I don't want the learner to just select OK without selecting the checkbox in order to replicate the sequence correctly. 
I have a slide which shows the message  which tells them as to what they did wrong when they select OK without checking the box, but when I tie that to the correct response, it will go there whether they select the checkbox or not.
I've tried adding multiple actions to the button, which doesn't work, becuase the OK button has to be tied to the learner conditionally selecting the checkbox to move on to the correct slide.  If I use multiple actions, and the first action is to SHOW  the slide with the incorrect message, if they correctly check the box and then hit OK, it will first SHOW them the incorrect slide.
I think what I need is a variable and then add an advanced action with a conditional statement.  However, I don't really know how to do that.  Here's the variable I created, but I don't know what value I should assign.  Here's the screen shot of the variable and conditional statement.  Could someone tell me how to do the variable and the conditional statement so that the learner when selecting OK WITHOUT selecting the checkbox first will be redirected the the error slide and if they select the checkbox FIRST, and then OK, they move on to the next screen?  Thanks,

Answer 1

Thanks, you definitely got me started on the right track on variables and advanced action statements.  The screen shots helped.
Here's how the actual fix went to make sure the OK button on the screen had a conditional statement attached to it, with
an advanced action:
I created parameters for the widget to link to the variable:
I created a variable:
Then I created an advanced action conditional statement for that variable which enabled the button to advance to the next slide when the clickbox was checked:
Then where I finally realized my final mistake was not setting the button properties to execute advanced action: