PET DICOM loading error

Operating system:11
Slicer version:5.6.2
Expected behavior:
Actual behavior:

When I loaded PET DICOM, I found this error what is meaning and what should i doTraceback (most recent call last): File “C:\Users\alnaseem\AppData\Local\slicer.org\Slicer 5.6.2\lib\Slicer-5.6\qt-scripted-modules\DICOMLib\DICOMUtils.py”, line 769, in get