phase fieldmaps not converting

My phase fieldmaps are not converting. The error was:

  File "build/bdist.linux-x86_64/egg/dcmstack/dcmmeta.py", line 1496, in from_dicom_wrapper
    nii_img = nb.nifti1.Nifti1Image(data, affine)
  File "/srv/software/python/EPD/virtualenvs/7.2/nipype0.5/lib/python2.7/site-packages/nibabel/spatialimages.py", line 317, in __init__
    self._header.set_data_dtype(data.dtype)
  File "/srv/software/python/EPD/virtualenvs/7.2/nipype0.5/lib/python2.7/site-packages/nibabel/analyze.py", line 578, in set_data_dtype
    'data dtype "%s" not recognized' % datatype)
HeaderDataError: data dtype "object" not recognized

Not sure why only my phase fieldmap datatypes are "object" instead of "int16" so I added a couple lines to get it convert. I don't think its the best fix though, so any suggestions would be appreciated!