Problem with a quiz score result returning blank

This is my quiz form https://form.jotform.com/80164863695164

The problem I am having is that the score field at the end will eventually be blank. The total score needs to be 70 or greater to show the submit button, otherwise it says "go back and try again".  I can go through it once, randomly select answers and get a certain score, then I go back to change some answers and check my score, eventually the score will just be blank.  Sometimes it changes, I go back and change some more, and then check the score and it's blank.  I can't narrow down the problem.  Please help.

Thanks

https://form.jotform.com/80164863695164

https://form.jotform.com/80164863695164

here are two other screen shots of working scores.

It is possible that the cause of the blank result is choosing an option that has an empty calculation value. Here is an example of one of the questions which options have empty calculation values:

I recommend to insert 0 for those choices.

If you have questions, please let us know.

When I entered 0 on those fields initially, they did not register, only the 1 did. So after the first few I didn't bother to enter 0 since it didn't show up.
Sent from my T-Mobile 4G LTE Device
...

I don't know why this happens, but you must persist until "0"'s are inserted. 

Anyway, I've managed to do that, so feel free to clone 

https://form.jotformeu.com/80173626530351

Thanks!  How do I clone it?

Hello fisheye4,

You can follow this guide for the steps on how to clone a form via the form URL: https://www.jotform.com/help/42-How-to-Clone-an-Existing-Form-from-a-URL

If you have additional questions, please let us know.

Thanks.