webPart.saveWebPartChanges() : Exception has been thrown by the target of an invocation

Hi,

I have this error "Exception has been thrown by the target of an invocation." when I execute the following code form my sharepoint hosted app. I think it's an security access error, but the app have full control access on the site collection.

        var clientContext = new SP.ClientContext(_spPageContextInfo.webAbsoluteUrl);
        var factory = new SP.ProxyWebRequestExecutorFactory(_spPageContextInfo.webAbsoluteUrl);
        clientContext.set_webRequestExecutorFactory(factory);
        var clientContextSite = new SP.AppContextSite(clientContext, _spPageContextInfo.siteAbsoluteUrl);

        var oFile = clientContextSite.get_web().getFileByServerRelativeUrl(PageUrl);
        var limitedWebPartManager = oFile.getLimitedWebPartManager(SP.WebParts.PersonalizationScope.shared);
        var webPart = limitedWebPartManager.get_webParts().getById(SPWebPartID);
        webPart.get_webPart().get_properties().set_item("JSLink", "[url]");
        webPart.saveWebPartChanges();

        clientContext.executeQueryAsync(Function.createDelegate(this, function () {
            //Done
        }), Function.createDelegate(this, function () {
            //TODO
        }));

Note: I used the same code without ProxyWebRequestExecutorFactory, and run direct on the site collection home page, and it is work without any issue:

function UpdateWPProp () {
        var clientContext = new SP.ClientContext();
        var oFile = clientContext.get_web().getFileByServerRelativeUrl((PageUrl););
        var limitedWebPartManager = oFile.getLimitedWebPartManager(SP.WebParts.PersonalizationScope.shared);
        var webPart = limitedWebPartManager.get_webParts().getById("SPWebPartID");
          webPart.get_webPart().get_properties().set_item("JSLink", "[URL]");
        webPart.saveWebPartChanges();

        clientContext.executeQueryAsync(Function.createDelegate(this, function () {
           //Done
        }), Function.createDelegate(this, function () {
           //Error
        }));
    };

any help would be appreciated