How to read Dicom using VTK from header

Hello, I have some issues when I try to read Dicom from header. I Have to files (File1.IMG and file2.hdr) and I’m using this code:
vtkSmartPointer< vtkDICOMImageReader > reader = vtkSmartPointer< vtkDICOMImageReader >::New();
reader->SetFileName(path_to_file1);
reader->Update();

There was a problem retrieving Data from : Path_to_File1

The same code works good when I use a set of dicom slices (file1.dcm, file2.dcm, file3.dcm…filen.dcm)
vtkSmartPointer< vtkDICOMImageReader > reader = vtkSmartPointer< vtkDICOMImageReader >::New();
reader->SetDirectoryName(path_to_serie);
reader->Update();

Do you have any idea about this issue please !!

thank you