Fields not being updated through the marketo SOAP API

Hi,

I am using the suds_marketo python SOAP API to sync marketo leads.  In my test case I am attempting to sync a single field called confluence_expertName.  When I sync the lead, I receive a response that the lead was updated correctly:

>>> client.sync_lead('atlassian@xxxx.com', (('confluence_expertName', 'string', 'Pix Software GmbH'),) )

(ResultSyncLead){

   leadId = 67xxxxx

   syncStatus =

      (SyncStatus){

         leadId = 67xxxxx

         status = "UPDATED"

         error = None

      }

   leadRecord = None

}

However, when I look at the record in Marketo, it remains unchanged.

Is there a reason that a field would not be updated, even though marketo API reports that the field has been updated.