deposited HI_Density error

Traceback (most recent call last):
  File "Fields_arbitrary.py", line 44, in <module>
    print(obj["deposit", "HI_Density"])
  File "/opt/apps/yt/yt-x86_64/src/yt-hg/yt/data_objects/data_containers.py", line 246, in __getitem__
    f = self._determine_fields([key])[0]
  File "/opt/apps/yt/yt-x86_64/src/yt-hg/yt/data_objects/data_containers.py", line 515, in _determine_fields
    finfo = self.ds._get_field_info(ftype, fname)
  File "/opt/apps/yt/yt-x86_64/src/yt-hg/yt/data_objects/static_output.py", line 543, in _get_field_info
    raise YTFieldNotFound((ftype, fname), self)
yt.utilities.exceptions.YTFieldNotFound: Could not find field '('deposit', 'HI_Density')' in RedshiftOutput0037.