The current OSPi 1.4 does not support B+ (the user manual has been updated to reflect this). A new version 1.4+ should be ready in a week or two, and it is tailored to B+.
Because it’s difficult to design one circuit that can fit both B and B+, we will offer both versions: OSPi 1.4 is for model A or B, and 1.4+ is for B+.