Language Declaration Error

I am recieving an error message when uploading my XLS form into the online form (https://opendatakit.org/xlsform/). The error message reads "The following language declarations do not contain valid machine-readable codes: English. Learn more: http://xlsform.org#multiple-language-support"

I have not specified language anywhere in the form. I also am only using one language. What is this error referring to and how do i fix it?

Thanks

could you please share part of your xls?

Yes, which part and how can I share it with you?

You can attach your full XLS file if you have no problem or part of your xls here.

odk_quality_improvement_mahama.01.21.2019.xls (217.5 KB)

You don't need to define default language English on settings sheet as your file contains only one language odk_quality_improvement_mahama.01.21.2019.xls (243.5 KB)

Thank you for your help!

I have same issue with my file.i have created the form on ODK build and then convert this form into XLSX. but when i convert back into xml i get this error.