same problem with io.imsave

Traceback (most recent call last):
  File "G:\Marwen\Summer.py", line 61, in <module> io.imsave("test.tif",summation, plugin="freeimage")
  File "C:\Python27\lib\site-packages\skimage\io\_io.py", line 129, in imsave return call_plugin('imsave', fname, arr, plugin=plugin, **plugin_args)
  File "C:\Python27\lib\site-packages\skimage\io\_plugins\plugin.py", line 88, in call return func(*args, **kwargs)
  File "C:\Python27\lib\site-packages\skimage\io\_plugins\freeimage_plugin.py", line 668, in imsave write(img, filename)
  File "C:\Python27\lib\site-packages\skimage\io\_plugins\freeimage_plugin.py", line 538, in write bitmap, fi_type = _array_to_bitmap(array)
  File "C:\Python27\lib\site-packages\skimage\io\_plugins\freeimage_plugin.py", line 604, in _array_to_bitmap raise ValueError('Cannot write arrays of given type and shape.')
ValueError: Cannot write arrays of given type and shape.

siggi