I am trying to use the Gainsight PX Data Loader python script to upload data that contains custom fields, but it is throwing an exception.  Is there a trick to referencing custom fields, like putting “custom.” in front of the field names?  Thanks.

{"apiKey":"xxxx","productKey":"xxxxxx","fieldMapping":{"USER":{"identifyId":"identifyId","firstName":"firstName","lastName":"lastName","email":"email","assessment_all":"assessment_all","assessment_finish":"assessment_finish","Assessment_inc":"Assessment_inc","Assessment_NS":"Assessment_NS","assessment_provrev":"assessment_provrev","assessment_todo":"assessment_todo"}}}

ERROR: Unknown field 'assessment_all' in fieldMapping in 'config.json'.  Valid Values: 'V'aptrinsicId', 'identifyId', 'type', 'gender', 'email', 'firstName', 'lastName', 'lastSeenDate', 'signUpDate', 'firstVisitDate', 'title', 'phone', 'score', 'role', 'subscriptionId', 'accountId', 'numberOfVisits', 'location.city', 'location.stateCode', 'location.stateName', 'location.countryCode', 'location.timeZone', 'location.coordinates.latitude', 'location.coordinates.longitude', 'createDate', 'lastModifiedDate', 'customAttributes', 'globalUnsubscribe', 'sfdcContactId']'

https://support.gainsight.com/PX/API_for_Developers/01About/Gainsight_PX_Data_Loader