Been there, done that! Part-timers are slower to adjust, but 11 months is the age for them to pull that trick for sure. I've just made it through two little criers and now they are happy at 14 & 15 months of age, whew! But the same thing, when I left the room they sat at the doorway gate and cried like they were heart-broken. It's happened to me many, many times, but the transition phase is always a different amount of time, days or weeks or months.