Set dataverse lookup field using a mapping data flow sink

Hello everyone, I'm getting to following error when trying to set the customerid lookup field in the opportunity entity. I'm using the mapping dataflow sink.

Any help would be appreciated. Thanks

Job failed due to reason: Error response from server: Some({"error":{"code":"0x80048d19","message":"Error identified in Payload provided by the user for Entity :'opportunities', For more information on this error please follow this help link https://go.microsoft.com/fwlink/?linkid=2195293 ----> InnerException : Microsoft.Crm.CrmException: Invalid property 'CustomerId' was found in entity 'Microsoft.Dynamics.CRM.opportunity'. ---> Microsoft.OData.ODataException: Does not support untyped value in non-open type.\r\n at System.Web.OData.Formatter.Deserialization.DeserializationHelpers.ApplyProperty(ODataProperty property, IEdmStructuredTypeReference resourceType, Object resource, ODataDeserializerProvider deserializerProvider, ODataDeserializerContext readContext)\r\n at Microsoft.Crm.Extensibility.CrmODataEntityDeserializer.ApplyStructuralProperty(Object resource, ODataProperty structuralProperty, IEdmStructuredTypeReference structuredType, ODataDeserializerContext readContext)\r\n --- End of inner excep