I have both Strelok (Basic) and just purchased Strelok Pro. Basic works perfectly. Strelok Pro with all information inputted (just as in basic) when I initiate Calculate, it only calculates elevation and not windage. In basic, when i initiate calculate, I get both elevation and windage. I'm running Strelok B&P on an IPOD 6 ver 10.3.2. I have not updated to IOS 11.