I can not complete the training on the Validation Tables. I have completed the challenge and answered correctly, but continue to receive an error from the system. I have checked my answer against answers of others that I work with and it matches exactly, they pass the challenge and I can not. My error reads: Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: REQUIRED_FIELD_MISSING, Required fields are missing: [Zip_Code__c]: [Zip_Code__c] 
Any thoughts?

I can not complete the training on the Validation Tables. I have completed the challenge and answered correctly, but continue to receive an error from the system. I have checked my answer against answers of others that I work with and it matches exactly, they pass the challenge and I can not. My error reads: Challenge Not yet complete... here's what's wrong: 
There was an unexpected error in your org which is preventing this assessment check from completing: System.DmlException: Insert failed. First exception on row 0; first error: REQUIRED_FIELD_MISSING, Required fields are missing: [Zip_Code__c]: [Zip_Code__c] 
Any thoughts?