InvalidCastException: Specified cast is not valid.

/** This is an automatically generated class by FairyGUI. Please do not modify it. **/

using FairyGUI;
using FairyGUI.Utils;

namespace Login
{
public partial class UI_LoginView : GComponent
{
public GGraph m_bgGraph;
public GTextField m_loginTxt;
public const string URL = "ui://gpt0jv85gio50";

public static UI_LoginView CreateInstance()
{
return (UI_LoginView)UIPackage.CreateObject("Login", "LoginView");//这一行报的错
}

public override void ConstructFromXML(XML xml)
{
base.ConstructFromXML(xml);

m_bgGraph = (GGraph)GetChildAt(0);
m_loginTxt = (GTextField)GetChildAt(1);
}
}
}
在CreateInstance返回的时候报的错