Better use a new method "private boolean clearFileName (String file)" checking (with logging) and setting the "fileName".

This method has to be used in the class FileAppender.java in:
- void setFile(String fileName, boolean append, boolean bufferedIO, int bufferSize)
- public void setFile(String file)

Also replace in clearFileName the Windows backslash: file.replace('\\', '/')
E.g. the install shield ask for the filename ("C:\mydir") and insert the result in the property list.