SerjoPerhaps I can, as the same thing happened to me. I wanted ONLY the base kit, nothing else, and for the life of me it would not let me join. You actually have to say "No, Thanks" to EVERY kit available. I guess if there is a kit you want, buy it (duh), but for the kits you do not want, you cannot simply pass over them. You actually have to scroll down, past Taiwanese Num Pad and Hebrew modifier kit, scroll and keep scrolling until you see "No, Thanks."
It's very confusing.