IDynamicMap 设置DynamicMapEnabled属性报错

下面的加载动态图层的代码在ArcGIS Engine10.3下运行过，没有问题
                customDynamicLayerClass pLayer = new customDynamicLayerClass();
                pLayer.Name = "dynamiclayer";
                pLayer.Visible = true;
                IActiveView pActiveView = axMapControl1.Map as IActiveView;
                IDynamicMap pDynamicMap = pActiveView.FocusMap as IDynamicMap;
                pDynamicMap.DynamicMapEnabled = true;
                axMapControl1.ActiveView.FocusMap.AddLayer(pLayer);
                pLayer.InvokeDynamic();
 
但现在ArcGIS Engine10.5下编译之后发现执行时 pDynamicMap.DynamicMapEnabled = true; 报错 com组件错误
 
有哪位朋友遇到过吗，请指点一下，感谢