log chunk showing error

logs.txt

		{
			 "Environment": "Prod",
			 "Region": "East US",
			 "time": "2017-12-20T19:09:01.3134767Z",
			 "resourceId": "/SUBSCRIPTIONS/8C449441-BBF5-40EE-BFAD-62B06ADC8EC5/RESOURCEGROUPS/AFFINITI/PROVIDERS/MICROSOFT.STREAMANALYTICS/STREAMINGJOBS/TESTINGEST",
			 "operationName": "Send Events: CosmosDB Output Prepare Data failure",
			 "category": "Execution",
			 "status": "Failed",
			 "level": "Error",
			 "properties": "{\"Error\":null,\"Message\":\"An error occurred while preparing data for CosmosDB. The output record does not contain the column '$pk' to use as the partition key property.\",\"Type\":\"DocumentDbOutputAdapterPrepareDataError\",\"Correlation ID\":\"77019b03-3468-4cf6-a8f7-c05125c4b3b0\"}"
		}