theHarvester not exporting report

./theHarvester.py -d targetdomain -l 1000 -b all -f output

I am using theHarvester python application to gather data on a site for pentesting purposes. Which works well. Accept I am unable to save them to html. The code above should save the results in output.html format.

I am using kali linux in a vm. I have to send the results to my instructor tomorrow. Please help.