Created Unassigned: Invalid URL Exception [14858]

Hi!

I have a problem, if I try to open an XLSX file with EPPlus. The File was created with Microsoft Office 2010.

My code is:

```
foreach (string fajl in fajlok)
{
FileInfo fn = new FileInfo(@fajl);
string indicated_user = fn.Name.Split('_')[0];
ExcelPackage ep = new ExcelPackage(fn);

Constans.GLOBALLOG.LogWrite(ep.Workbook.Worksheets.Count().ToString());
if (ep.Workbook.Worksheets.Count() == 3)
{
.....
```

The Exception occurs at ep.Workbook.Worksheets.Count().
I read, that this problem has already fixed, however, it happened...

Is any fix for this problem?
I use the latest DLL version: EPPlus 3.1 Apr 11, 2012, Stable

Thanks for the answer!
Zsolt Abdai