I tried opening your so called XLS file and found errors in MS Excel too, so your file is not a standard XLS file that MS Excel supports for doing your way. We follow MS Excel standards, so you may get the error opening such a file via Aspose.Cells APIs.
I am not entirely sure about the process you are using? Are you taking your attached HTML file into the streams and then create a new file (you are trying to create a new XLS file but this might not the correct way) first and then write the html data/contents to it. Now you are using Aspose.Cells.Workbook object to open/load the file.
Here is the sample (runnable) code that I tried:
StreamReader rd = new StreamReader(“e:\test2\veerugr.html”);
string input = rd.ReadToEnd();
//formatHTMLTable(); – Not sure about this method either.
file = new StreamWriter(“e:\test2\Veeru.xls”); // This line will not create a native Excel file, so its format would be unknown. MS Excel will give error opening into it.
Workbook workbook = new Workbook(“e:\test2\Veeru.xls”); //Got error: This file’s format is not supported or you don’t specify a correct format.