Update Entity using Odata Javscript in HTML WebResource

Hello Expert i am doing an update operation using Odata . but i  am getting Error  value=Error processing request stream. The request should be a valid top-level resource object.Here is my code below. Please suggest where i am wrong.

 function UpdateRecord() {
                    
    var ODataPath = serverurl + "/XRMServices/2011/OrganizationData.svc";
    var id = "d6934b7c-c33e-e211-81e4-080027e18ca8";//record Id
    var updateRecord = {};
    updateRecord .programId = userId; //ContactId
    updateRecord .LogicalName = "contact";    
    updateRecord .field1= parseFloat(99.00);//Money type
    updateRecord .field2= parseFloat(89.51);//Money type
    updateRecord .field3= parseFloat(85.21);//Money type
    var updateEntityRequest = new XMLHttpRequest();
    updateEntityRequest .open("POST", ODataPath + "/EntityprogramSet(guid'" + id + "')", true);
    updateEntityRequest .setRequestHeader("Accept", "application/json");
    updateEntityRequest .setRequestHeader("Content-Type", "application/json; charset=utf-8");
    updateEntityRequest .setRequestHeader("X-HTTP-Method", "MERGE");
 
    updateEntityRequest .onreadystatechange = function () {
        onRecordUpdateCallBack(this, id);
    };
    updateEntityRequest.send(JSON.stringify(updateRecord));
 
}
 
function onRecordUpdateCallBack(updateEntityReturnValue, recId) {
    if (updateEntityReturnValue.readyState == 4 /* complete */) {
        if ((updateEntityReturnValue.status == 204) ||
            (updateEntityReturnValue.status == 1223)) {
            alert("Record with Id : " + recId+ " updated successfully.");
        }
        else
            alert("Error occurred while updating record.");
    }
}

Thank you

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saroj