Import Error: Empty values for mandatory fields - Closing Date

Import Error: Empty values for mandatory fields - Closing Date

Hello, 

I've tried multiple times to import a CVS Potential list from another Zoho account. But the error message I get is: 

Empty values for mandatory fields - Closing Date

There are valid dates in this field, so I don't understand why this error messages comes up, and it won't import. It's in the format Zoho exports CVS files in, so it should not have any problems reading it.. any suggestions? 

Thanks!

    Nederlandse Hulpbronnen