diff --git a/src/Core/Services/TestAutomationHttpService.cs b/src/Core/Services/TestAutomationHttpService.cs
index c9293c3..cf7e26f 100644
--- a/src/Core/Services/TestAutomationHttpService.cs
+++ b/src/Core/Services/TestAutomationHttpService.cs
@@ -2823,7 +2823,10 @@ namespace NavisworksTransport.Core.Services
 
                 if (!IsSameModelItem(animationViewModel.SelectedAnimatedObject, realObject))
                 {
-                    throw new InvalidOperationException("选择真实物体失败：动画视图模型未保留选中的对象");
+                    string detail = animationViewModel.SelectedAnimatedObject == null
+                        ? "选择真实物体失败：物体在当前文档不可用（fragment 姿态解析失败，常见于导出局部模型中的嵌套实例物体；请改用虚拟物体或单层结构物体）"
+                        : "选择真实物体失败：动画视图模型未保留选中的对象";
+                    throw new InvalidOperationException(detail);
                 }
 
                 animatedObjectPayload = new