In order to better investigate and/or report a problem to developers at MongoSluice, you can change the debug settings of simplelogger.properties.
Change your directory to the mongosluice directory and then to conf. Open simplelogger.properties with your favorite text editor. You should see this:
There are three different settings for logger properties: info, debug, and trace located on line two. Info is the default and most basic setting, debug provides more developer output, and trace provides extremely detailed feedback. The output after running a job will be written to /tmp/mongosluice.log.