Can't load xll programmatically

Question

I\'m trying to automating some tests for an Excel add-in, which is in xll form. I have some problem in loading the xll. I\'m writing it in C# and my code looks like this:

Answer 1

Thanks for all the suggestions.

I solved the problem by changing the default file path for the Excel application.

Application.xlApp = new ApplicationClass();
xlApp.DefaultFilePath = "C:\\SomePath";
xlApp.RegisterXLL("Whatever.xll");