[Samson]

Нашел где скрывается незадача. При создании объекта его значение не учитывается, а при его редактировании в расчете суммы учитывается старое значение из базы.
К сожалению, плагины это пока еще не мой профиль, мне и скрипты толком пока не удалось понять.

Вот выдрал из sdk два подходящих скрипта и приспособил под свои нужды.

// Prepare variables for updating .
var id = crmForm.all.new_invoice.DataValue[0].id;
var authenticationHeader = GenerateAuthenticationHeader();

// Prepare the SOAP message.
var xml = "<?xml version='1.0' encoding='utf-8'?>"+ 
"<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/'"+
" xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'"+
" xmlns:xsd='http://www.w3.org/2001/XMLSchema'>"+ 
authenticationHeader+ 
"<soap:Body>"+ 
"<RetrieveMultiple xmlns='http://schemas.microsoft.com/crm/2007/WebServices'>"+ 
"<query xmlns:q1='http://schemas.microsoft.com/crm/2006/Query'"+
" xsi:type='q1:QueryExpression'>"+ 
"<q1:EntityName>new_payment</q1:EntityName>"+ 
"<q1:ColumnSet xsi:type='q1:ColumnSet'>"+ 
"<q1:Attributes>"+ 
"<q1:Attribute>new_summ</q1:Attribute>"+ 
"</q1:Attributes>"+ 
"</q1:ColumnSet>"+ 
"<q1:Distinct>false</q1:Distinct>"+ 
"<q1:Criteria>"+ 
"<q1:FilterOperator>And</q1:FilterOperator>"+ 
"<q1:Conditions>"+ 
"<q1:Condition>"+ 
"<q1:AttributeName>new_invoice</q1:AttributeName>"+ 
"<q1:Operator>Like</q1:Operator>"+ 
"<q1:Values>"+ 
"<q1:Value xsi:type='xsd:string'>"+id+"</q1:Value>"+ 
"</q1:Values>"+ 
"</q1:Condition>"+ 
"</q1:Conditions>"+ 
"</q1:Criteria>"+ 
"</query>"+ 
"</RetrieveMultiple>"+ 
"</soap:Body>"+ 
"</soap:Envelope>";
// Prepare the xmlHttpObject and send the request.
var xHReq = new ActiveXObject("Msxml2.XMLHTTP");
xHReq.Open("POST", "/mscrmservices/2007/CrmService.asmx", false);
xHReq.setRequestHeader("SOAPAction","http://schemas.microsoft.com/crm/2007/WebServices/RetrieveMultiple");
xHReq.setRequestHeader("Content-Type", "text/xml; charset=utf-8");
xHReq.setRequestHeader("Content-Length", xml.length);
xHReq.send(xml);
// Capture the result.
var resultXml = xHReq.responseXML;

// Parse and display the results.

 if (results.length == 0)
 {}
 else
 {
  var summa = 0
    for (i=0;i < results.length;i++)
    {
     summa = summa + parseFloat(results[i].selectSingleNode('./q1:new_summ').nodeTypedValue); 
    }

// Prepare the SOAP message.
var xml = "<?xml version='1.0' encoding='utf-8'?>"+ 
"<soap:Envelope xmlns:soap='http://schemas.xmlsoap.org/soap/envelope/'"+
" xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance'"+
" xmlns:xsd='http://www.w3.org/2001/XMLSchema'>"+ 
authenticationHeader+
"<soap:Body>"+ 
"<Update xmlns='http://schemas.microsoft.com/crm/2007/WebServices'>"+ 
"<entity xsi:type='invoice'>"+ 
"<ec_totalpayment>"+atr+"</ec_totalpayment>"+ 
"<invoiceid>"+id+"</invoiceid>"+ 
"</entity>"+ 
"</Update>"+ 
"</soap:Body>"+ 
"</soap:Envelope>";
// Prepare the xmlHttpObject and send the request.
var xHReq = new ActiveXObject("Msxml2.XMLHTTP");
xHReq.Open("POST", "/mscrmservices/2007/CrmService.asmx", false);
xHReq.setRequestHeader("SOAPAction","http://schemas.microsoft.com/crm/2007/WebServices/Update");
xHReq.setRequestHeader("Content-Type", "text/xml; charset=utf-8");
xHReq.setRequestHeader("Content-Length", xml.length);
xHReq.send(xml);
// Capture the result
var resultXml = xHReq.responseXML;