c# - C1Excel error on load excel file

Question

I tried to load excel file using C1Excel. Everything works fine until I loaded excel file and had activex with it. The error said:

This file cannot be read because it is password-protected.

But, It is no need password to open the file. The code is below.

C1XLBook book = new C1XLBook();
book.Load("excelfile.xls"); //Here is the error code appear
foreach (XLSheet loopSheet in book.Sheets)
{
    //code
}

So, if anyone ever find this problem and solved it, please to share.

I have tried that file can be loaded by Microsoft.Office.Interop.Excel. Is there any method or something that C1Excel can load data from it. I wish I could use Microsoft.Office.Interop.Excel to replace C1Excel, but the project has code already with C1Excel every where.

Thank you