EPPPlus cannot open RDLC rendered to EXCELOPENXML - rdlc

Question

Does anyone have any idea , or even a solution, to open an xlsx file using EPPlus created from an rdlc report.
At the moment, when I try to do this I get an null exception when I try to access the worksheets.
// filename is the xlsx file created by exported rdlc to excel
FileInfo newFile = new FileInfo(filename);
ExcelPackage pck = new ExcelPackage(newFile);
// I get error here
pck.Workbook.Worksheets.Add("New Sheet");

Answer 1

If you intention is to add onto the file you are using the wrong constructor. The one you are using now is for creating a new package off of a template. The on your want is this (without the extra Boolean) which will open the file directly:
ExcelPackage pck = new ExcelPackage(newFile);
Response to Comments
#A.Ellwood I just tried it with the file you posted and it works fine for me. Here is the code I used:
[TestMethod]
public void RDLC_Test()
{
var datatable = new DataTable("tblData");
datatable.Columns.AddRange(new[]
{
new DataColumn("Col1", typeof (int)), new DataColumn("Col2", typeof (int)),
new DataColumn("Col3", typeof (object))
});
for (var i = 0; i < 10; i++)
{
var row = datatable.NewRow();
row[0] = i;
row[1] = i*10;
row[2] = Path.GetRandomFileName();
datatable.Rows.Add(row);
}
var fi = new FileInfo(#"c:\temp\Report1.xlsx");
using (var pck = new ExcelPackage(fi))
{
var workbook = pck.Workbook;
var worksheet = workbook.Worksheets.Add("Sheet1");
worksheet.Cells.LoadFromDataTable(datatable, true);
pck.Save();
}
}