Namespace error OfficeOpenXML EPPlus

I had only installed DocumentFormat.OpenXml and the reference would not work despite following other sources on the net.

I had to install, through NuGet, both DocumentFormat.OpenXml AND EPPlus to get the reference to work.

That fixed this for me.

I believe this is just a problem of casing. This:

using OfficeOpenXML;

should be:

using OfficeOpenXml;

Note the lower case "M" and "L" at the end.

I say that based only on the sample code...