Running assertions fail in 1.2.1

[sujithemmanuel]

All the needed packages listed in requirements.txt were installed and setup is also successful. After that running assertions fail. Any pointers?
Running assertions on SUT system1.domain1.com...
Traceback (most recent call last):
File "/Redfish-Service-Conformance-Check/rf_client.py", line 702, in
main()
File "/Redfish-Service-Conformance-Check/rf_client.py", line 694, in main
rfs_test.run(sut)
File "/Redfish-Service-Conformance-Check/rfs_test/init.py", line 38, in run
log.assertion_log('OPEN', None, sut.SUT_prop, sut.Redfish_URIs['Service_Root'])
File "/Redfish-Service-Conformance-Check/logger.py", line 413, in assertion_log
self.open_assertions_xl()
File "/Redfish-Service-Conformance-Check/logger.py", line 231, in open_assertions_xl
self.XlAssertionSheet = self.XlAssertionWb.get_active_sheet()
AttributeError: 'Workbook' object has no attribute 'get_active_sheet'