This may be caused by a couple issues
1) You must go through all the modules before you can take the quiz so please ensure that you have gone through each and clicked the next module at the bottom- you can also check this at the dashboard on the side navigation bar under modules
2) Your browser may be pulling from a previous cache version of the site, please clear your cache and try again. You can also access the quiz from the side navigation bar (three stacked bars next to the logo at the top) and click module in the drop down, choose the module you are currently on.
If you are still having issues please email us at [email protected]