Please make sure you are using the correct Salesforce object field API names. Some standard fields like Opportunity Stage have a different API name from the label, in this case it would be StageName. If you are using custom fields, please make sure you add "__c" to the field label. All fields need to be comma separated, for example "Name,Phone,BillingCity,BillingStreat,Industry,Status__c". Please make sure there are no duplicate fields selected.