Why doesn't dicomparse read my dicom file?

By following the suggestions in this thread i copied the file dicomparse from "/toolbox/images/iptformats/private" to my working directory. This solution is very suitable for my needs, since I only need the AquisitionTime, RescaleSlope, RescaleIntercept and InstanceNumber tags from the dicom header. When I tried to run it, dicomparse crashed matlab, which was forced to quit.

I managed to solve this, somewhat crudely, by copying the rest of the files in the same folder, also into my working directory. dicomparse no longer crashes, but returns an empty 0x1 struct. Providing the exact same path to dicominfo or dicomread works perfectly fine, so it has to be a problem related to dicomparse.

This would be a lot easier to solve if dicomparse wasn't private.