Hi
From my understanding, you are facing issue when loading mat file in python.
Loading mat files can cause an error if the version is not compatible with SciPy. Please check your mat file version using the following command:
dbtype filename 1
If the output contains Matlab 7.3 then your file is not compatible, and this needs hdf5 python library.
If version is 5.0 or nothing is specified, then your code should work fine.