I've also had problems with Tozando, but since it was the same problem I had with Bu Jin (the hakama was shorter than I expected), I can only conclude I've been wearing it wrong. Then again, if when I try to adjust it's still short and unstable.
you definitely don't want to wear an unstable hakama. it might explode and makes you do ukemi for no good reason at all. and the way to deal with short hakama is to cut it further up above the knee. it looks better that way.