Created Unassigned: Object reference not set to an instance of an object when copying a worksheet with header image [14904]

Hello:

First of all, congratulations for this project!! It's a very powerful tool!!!

I have a problem when I try to copy a worksheet which contains an image on the header. The build is successfull but when I invoke the method package.Workbook.Worksheets.Add an exception is thrown.

The stack trace shows the following
at OfficeOpenXml.ExcelWorksheets.CopyHeaderFooterPictures(ExcelWorksheet Copy, ExcelWorksheet added)\r\n at OfficeOpenXml.ExcelWorksheets.Add(String Name, ExcelWorksheet Copy)\r\n at Tts.WebInterface.WebFunctions.GenerarInformeExcel(eTipoInforme p_eTipoInforme, ConnectedDatabaseCommunicationLayer& p_DatabaseComunication, FileInfo p_FileInfo) in C:\\Desarrollo\\Proyectos\\BTA\\TTS\\TTSWebInterface\\TTSWebInterface\\TTSWebFunctions.cs:line 1671\r\n at Tts.WebInterface.EstadoEjecucionEscenario.btnDownloadReport_Click(Object sender, EventArgs e) in C:\\Desarrollo\\Proyectos\\BTA\\TTS\\TTSWebInterface\\TTSWebInterface\\EstadoEjecucionEscenario.aspx.cs:line 135

Attached you will find the excel file.

I'm using epplus 3.1.3.

I hope this helps.

Thanks in advance.