I'm investigating using a .Net Assembly that our C# based web app uses, within our PowerBuilder desktop app. I am getting the following message from the CreateInstance function:

Constructor on type 'OfficeOpenXml.ExcelPackage' not found.

This code is the vendor's simple Hello World example:

// var file = new FileInfo(@"c:\temp\myWorkbook.xlsx");
// using(var package = new ExcelPackage(file))
// {
//    var sheet = package.Workbook.Worksheets.Add("My Sheet");
//    sheet.Cells["A1"].Value = "Hello World!";
// 
//    // Save to file
//    package.Save();
// }

I tried using the .Net Importer and regular script as seen below and got the same error. I got the classname from the generated object. I am passing the file name as an argument to CreateInstance just like the C# snippet does. What do I need to do differently?

DotNetAssembly ldn_Assembly
DotNetObject ldn_Package
Long ll_return
String ls_dllfile, ls_classname

ls_dllfile = "C:\PBSource\PB2021\EPPlus\EPPlus.dll"
ls_classname = "OfficeOpenXml.ExcelPackage"

ldn_Assembly = Create DotNetAssembly

ll_return = ldn_Assembly.LoadWithDotNetFrameWork(ls_dllfile)
If ll_return < 0 Then
   Messagebox("Load Assembly Failed", ldn_assembly.ErrorText, StopSign!)
   Return
End If

ldn_Package = Create DotNetObject

ll_return = ldn_Assembly.CreateInstance(ls_classname, ldn_Package, ls_dllfile)
If ll_return < 0 Then
   Messagebox("Create Instance Failed", ldn_assembly.ErrorText, StopSign!)
   Return
End If

Destroy ldn_Assembly
Destroy ldn_Package