Ошибка при звонке

function OnOktellCommunicate(StringParam) {
	var OktellXmlDom = OktellGetXmlDom();
	MsxmlParseXmlString(OktellXmlDom, StringParam);
	WriteOktellLog('FullLog' + DateToStr(new Date().getVarDate(), '_'), 
		'OnOktellCommunicate: ', StringParam);
	var RootNode = OktellXmlDom.selectSingleNode('//event');
	if (!RootNode) {
		return;
	}
	var EventID = MsxmlGetXmlAttributeValueByName(RootNode, 'id');
	switch (EventID) {
		case ocmUserStateChanged:
			OktellProcessUserStateChanged(RootNode);
			break;
		case ocmRingStarted:
			OktellProcessRingStarted();
			break;
		case ocmCommutationStarted:
			OktellProcessCommutationStarted(RootNode);
			break;
		case ocmRingFinished:
			OktellProcessRingFinished(RootNode);
			break;
		case ocmFlashHoldAction:
			OktellProcessFlashHoldAction(RootNode);
			break;
		case ocmACMStarted:
			OktellProcessACMStarted(RootNode);
			break;
		case ocmChainStateChange:
			OktellProcessChainStateChange(RootNode);
			break;
		case ocmLineStateChange:
			OktellProcessLineStateChanged(RootNode);
			break;
		case ocmFaxFilesReceived:
			OktellProcessFaxFilesReceived(RootNode);
			break;
	}
 
}