sub modules missing?

In [48]: import skimage. skimage._osp skimage.util skimage.version In [48]: import skimage. and: In [46]: from skimage import exposure --------------------------------------------------------------------------- ImportError Traceback (most recent call last) /Users/maye/Dropbox/src/pymars/<ipython-input-46-fda3143d69ce> in <module>() ----> 1 from skimage import exposure ImportError: cannot import name exposure In [47]: skimage.__version__ Out[47]: '0.6dev' What happened here? Please help. Best regards, Michael