Hi All, 

Im trying to do the second challenge in App Customization  but am getting some Super badge am getting the error "Challenge Not yet complete... here's what's wrong:  Couldn’t find the 'Volunteer Shift' relationship field or it is not configured correctly."
Please, anyone, can anyone tell me which relationships should be created between these objects? I have created a master-detail relationship between them. 


Also, am not clear with this "Shifts with cascading delete and the option of roll-up summary fields." 

Thank you and any help is appreciated.
Thank you in advance.