Hi - just downloaded & tried this app. It looked up exchange rates OK, but then failed with the message "Index was outside the bounds of the array". Changing currency didn't seem to make any difference.
I am using it with a single app's data - the text files reporting daily and weekly sales as downloaded from Apple. I first pointed it to a folder in which I have separate subfolders holding daily and weekly reports. I also tried pointing it directly to the subfolder holding all the daily reports. This also didn't make any difference. Same error message.