Unreadable content EPPlus

This morning i have worked with EPPlus in my application MVC 3.

using (ExcelPackage pck = new   ExcelPackage(fileInfoNew,fileInfoTemplate))
            {  pck.Save(); }

When the file generated is saved and opened, i got this error:

"unreadable content", around "xl/styles.xml".

After some time,I have tested by app with the blank .xlsx file.. and I have the same result!

Google helped me: Epplus 3.1.2 has bug! Now, with the version 3.1.1, my app worked!