If I understand you correctly, you tested everything out in one application and then put the config and the dll into a new application and now nothing works. It sounds to me like you might not have done all of the work in your code that you need to do. For example, did you set up your GetLogger variable correctly? Are you actually making any calls to the logger?
I'm really not a fan of trying to copy a whole config. Instead, I would rather see you copy just the log4net portion that you need. Otherwise, you can easily introduce issues.
I wrote an aricle about a year ago that walks you through log4net step by step and explains each step. Maybe if you walk through each step and compare it against your non-working application, you will see where the trouble is. Here is the link to the article:
log4net Tutorial[
^]