Excel New Cases Import Issue

Hello All,

I just tried to import an excel document in the hopes of creating new cases
in one of my applications. I passed the first step where you choose your
excel file with no problems, but on step 2, I am not able to choose
anything from the "Excel column" dropdown menu. It comes up blank. Then if
I try to continue, I get an error message. I have attached screenshots of
both of these incidents and a sample of my spreadsheet below. We have the
necessary standard subscription, and we have tried to adjust different
things, but we cannot get it to work. Any assistance would be greatly
appreciated.

Thanks,
Eric