Were you sure both had completed building? I know, many times I will queue up the research and be able to "build" the stabilizers, but they wont actually build until the research is completed. Thats the only thing I can think of. Otherwise, there could be a bug, but I've never had problems with these jumps without not having it researched yet thinking I did. Anyway, when they work, they work fantastically. Anything that saves a few jumps is worth it in my mind. Helps in outflanking the enemy. I just wish they worked between different systems. Still have to go through the star to jump systems. Oh well.