Want to convert Excel file to PDF using Spire.Xls but throws a Reflection Exception

Just want to use Spire to get an Excel file and save as PDF:

            Workbook workbook = new Workbook();
            workbook.LoadFromFile(@"D:\excels\Report.xlsx", ExcelVersion.Version2016);
            workbook.SaveToFile(@"D:\excels\" + name + ".pdf", Spire.Xls.FileFormat.PDF);

but throws the following exception at the first line:

I have set copy to local to true in all references but still throws the exception.

Any ideas?

Thanks