trying to open the attached workbook with this code:

Telerik.Windows.Documents.Spreadsheet.Model.Workbook workbook;
using (Stream input = File.OpenRead("sample.xlsx"))
{
  var provider = new Telerik.Windows.Documents.Spreadsheet.FormatProviders.OpenXml.Xlsx.XlsxFormatProvider();
  // The import method enables you to also pass a byte[] with the XLSX document data
  workbook = provider.Import(input, TimeSpan.FromSeconds(30));
}

I get an unhandled exception:

An unhandled exception of type 'System.ArgumentNullException' occurred in Telerik.Documents.Spreadsheet.dll
Value cannot be null.

Any idea what's going on?

Thank you for your time,

Phil

This would allow repeating header rows on every printed page. More information related to this functionality may be found on the following link:

https://support.office.com/en-us/article/Print-rows-with-column-headers-on-top-of-every-page-d3550133-f6a1-4c72-ad70-5309a2e8fe8c