Not all steps are connected

Your steps aren’t connected

If you go into Flow View, you’ll be able to see how your steps connect to one another.  If your steps are not connected, your form will not work.  

To connect the steps, click on each step, ensure that you are in the steps tab, and then click on Select a target step.  The target step is the step that comes right after that particular step. 

If you have a form step, you would simply scroll down to the select a target step section.

If you have a question step, you would click on your step, then scroll down to your responses.  Then hit the pencil icon (edit), scroll down to select a target step, and then click "save response".  You will continue to do this for each of your responses.