Since LIFA is old and no longer supported, I'd recommend that you upgrade to LINX for communicating with your Arduino. After doing so, and you are still unable to get it to work, please post on the LINX forums. When you post on the forums, you will need to provide more information especially including any errors that you get when you run your VI.
When using LINX, you won't need to set the "pin mode" which will probably solve your problem.