Pick Many

I have a checklist where I would like the learner to have the opportunity to check each box before moving to the next slide.  Here is what is happening:

If some boxes are not checked and the submit button is clicked the incorrect layer will display. (so far so good).  The next slide will then display - if the user goes back to the checklist they are not able to check the remaining boxes.

I would like the checklist to stay on the screen in the case of an incorrect and allow the user to click the remaining boxes.

Any ideas would be welcome - thank you very much.