The file is fine. Unless you've combined other hacks with PRS+, we have to investigate what's wrong. Create user.config file in /database/system/prsplus/ folder with the following content
Code:
var config = Utils.config;
config.defaultLogLevel = "trace";
config.logFile = "/Data/PRSPlus.log";
It should create PRSPlus log in the root of internal memory. Check it's content. (when we resolve this issue, don't forget to delete the user.config file)