Operate many times, but only the first takes effect

I use dataProcessor with dhtmlxTree. When I edit one node, the database updates. But when I edit some nodes, only the first I edited submit to the database and the others don’t. Why? Code is like:

    // w1 is a dhtmlxWindow
    var toolbar = w1.attachToolbar();
    authGroupTree = w1.attachTree();
    var myDP = new dataProcessor("authGroupAction!hotelGroup.action");

Please double-check the server side response, it must be an XML in the incorrect format.
If response is invalid - it may break the data saving for next items.

Yes. I add the response header, and It works.