dsp.MatFileReader HDF5 library encountered an error

Hi all, I am getting this error with MatFileReader which I don't know how to fix. The function below simply reads a mat file with dsp.MatFileReader.

S.A = randn(1000,1);
S.B = randn(1000,1);
save('sampleS.mat','S','-v7.3');

clear S;

filename = 'sampleS.mat';
VariableName = 'S';
SamplesPerFrame = 50;

mfr = dsp.MatFileReader;
mfr.Filename = filename;
mfr.VariableName = VariableName;
mfr.SamplesPerFrame = SamplesPerFrame;

while ~isDone(mfr)
    x= mfr();
    d = x.A;
end


Error using dsp.MatFileReader/setupObject (line 195)
The HDF5 library encountered an error and produced the following stack trace information:

    H5D__open_name    not a dataset

Error in dsp.MatFileReader/setupImpl (line 212)
            setupObject(obj,varargin);

Error in matlab.system.mixin.FiniteSource/isDone

Error in untitled (line 17)
while ~isDone(mfr)