C#脚本模块出错，未将对象引用设置到对象的实例

自定义了窗口

xmal代码为

<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:hc="https://handyorg.github.io/handycontrol"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:qk="https://getquicker.net"
        Width="400"
        Height="150"
        Title="调节透明度"
        mc:Ignorable="d">
  <Grid Margin="5">
    <StackPanel>
          <Slider x:Name="MySlider" Minimum="0" Maximum="255"
                  Value="128"
                LargeChange="64" SmallChange="32"   
                TickPlacement="BottomRight" TickFrequency="16"
                HorizontalAlignment="Stretch"
                />
    </StackPanel>
  </Grid>
</Window>

c#代码为

using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Forms;
using System.Collections.Generic;
using MessageBox = System.Windows.Forms.MessageBox;
using Quicker.Public;

public static IDictionary<string, object> dataContext;
public static ICustomWindowContext winContext;
public static Slider MySlider;

public static void OnWindowCreated(Window win, IDictionary<string, object> winData, ICustomWindowContext winContext){
    MySlider = win.FindName("MySlider") as Slider;
    MySlider.ValueChanged += MySlider_ValueChanged;//注册MySlider_ValueChanged事件
    winContext.RunSp("tiaojie", new Dictionary<string,object>{{"alpha", MySlider.Value}});
}
public static void MySlider_ValueChanged(object sender, RoutedPropertyChangedEventArgs<double> e)
{
    winContext.RunSp("tiaojie", new Dictionary<string,object>{{"alpha", e.NewValue}});
}

载入窗口时调用 tiaojie 模块可以使用

但在使用 MySlider_ValueChanged 回调函数 去出现错误，如何解决呢，望大佬们给点意见