Can not get dicom tag

I want to read a dicom tag, and the code is:

import SimpleITK as sitk
reader = sitk.ImageFileReader()
reader.SetFileName(path)
reader.LoadPrivateTagsOn()
reader.ReadImageInformation()
val = reader.GetMetaData('0040|9225')

It return an error as:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "D:\Anaconda3\envs\general\lib\site-packages\SimpleITK\SimpleITK.py", line 8765, in GetMetaData
    return _SimpleITK.ImageFileReader_GetMetaData(self, key)
RuntimeError: Exception thrown in SimpleITK ImageFileReader_GetMetaData: D:\a\1\sitk-build\ITK\Modules\Core\Common\src\itkMetaDataDictionary.cxx:88:
itk::ERROR: Key '0040|9225' does not exist

Then, I open the file using radiant:

So, how can I obtain the ‘0040|9225’?

Seems to only support the top level tags. I also asked a few questions about that in the past, seems we should fix that.