doing above steps, function export_responses
will respond this surveyresponse with appropriate token

using: export_responses_by_token (applying this token, DocumentType='doc')
will respond no Data! empty response

FOUND THE PROBLEM IN:
In survey-table there are 2 rows for this token:
First is not completed corresponding to above steps
Second with higher primary-id is completed

function export_responses returns correctly token and the second (higher) tid (primary id)

function export_responses_by_token seems to return the values of the first entry found, which is not completed. It should expand the where clause with 'completed <> null' (not null)

=========================================================================
for my usage i made the following extension:
I added a changed function in remotecontrol_handle.php
function export_responses_by_id

It is a copy of function export_responses_by_token
and uses the tid instead of the token.
The tid is always unique and so it was the better way to retrieve a single response.

/**
 * RPC Routine to export token response in a survey.
 * Returns the requested file as base64 encoded string
 *
 * @access public
 * @param string $sSessionKey Auth credentials
 * @param int $iSurveyID Id of the Survey
 * @param string $sDocumentType pdf,csv,xls,doc,json
 * @param string $iTid Primary-Table-ID
 * @param string $sLanguageCode The language to be used
 * @param string $sCompletionStatus Optional 'complete','incomplete' or 'all' - defaults to 'all'
 * @param string $sHeadingType 'code','full' or 'abbreviated' Optional defaults to 'code'
 * @param string $sResponseType 'short' or 'long' Optional defaults to 'short'
 * @param array $aFields Optional Selected fields
 * @return array|string On success: Requested file as base 64-encoded string. On failure array with error information
 *
 */
public function export_responses_by_id($sSessionKey, $iSurveyID, $sDocumentType, $iTid, $sLanguageCode=null, $sCompletionStatus='all', $sHeadingType='code', $sResponseType='short', $aFields=null)
{
    if (!$this->_checkSessionKey($sSessionKey)) return array('status' => 'Invalid session key');
    if (!Permission::model()->hasSurveyPermission($iSurveyID, 'responses', 'export')) return array('status' => 'No permission');
    if (!tableExists('{{survey_' . $iSurveyID . '}}')) return array('status' => 'No Data');
    if(!$oResult = SurveyDynamic::model($iSurveyID)->findByAttributes(array('id' => $iTid))) return array('status' => 'No Response found for Tid');
    if ($oResult['id'])
    {
        return $this->export_responses($sSessionKey, $iSurveyID, $sDocumentType, $sLanguageCode, $sCompletionStatus, $sHeadingType, $sResponseType, $oResult['id'], $oResult['id'], $aFields);
    }
}