C# 使用html agility pack获取img src值

我试图从下面的html中获取img src图像链接的值。我已经尝试过c#like bellow，但这没有抓住链接。我在c#做什么。有人能帮我吗

C#：

Html:

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您可以共享包含原始url的代码吗？下面是我试图从我看到的运行时异常（第13行）中获取数据的页面：'gzip'不是受支持的编码名称。有关定义自定义编码的信息，请参阅encoding.RegisterProvider方法的文档。参数名称：name

Picture = htmlDoc.DocumentNode.SelectSingleNode("//div[@id='imgTagWrapperId']/img").Attributes["src"].Value;

<div id="imgTagWrapperId" class="imgTagWrapper" style="height: 700px;">
                <img alt="PET N PET 1080 Counts Large Green Dog Waste Bags Unscented 60 Rolls Doggie Refill Bags" src="https://images-na.ssl-images-amazon.com/images/I/61xdgCf5UBL._SX679_.jpg" data-old-hires="https://images-na.ssl-images-amazon.com/images/I/61xdgCf5UBL._SL1001_.jpg" class="a-dynamic-image  a-stretch-vertical" id="landingImage" data-a-dynamic-image="{&quot;https://images-na.ssl-images-amazon.com/images/I/61xdgCf5UBL._SX466_.jpg&quot;:[466,466],&quot;https://images-na.ssl-images-amazon.com/images/I/61xdgCf5UBL._SX569_.jpg&quot;:[569,569],&quot;https://images-na.ssl-images-amazon.com/images/I/61xdgCf5UBL._SX425_.jpg&quot;:[425,425],&quot;https://images-na.ssl-images-amazon.com/images/I/61xdgCf5UBL._SY355_.jpg&quot;:[355,355],&quot;https://images-na.ssl-images-amazon.com/images/I/61xdgCf5UBL._SY450_.jpg&quot;:[450,450],&quot;https://images-na.ssl-images-amazon.com/images/I/61xdgCf5UBL._SX679_.jpg&quot;:[679,679],&quot;https://images-na.ssl-images-amazon.com/images/I/61xdgCf5UBL._SX522_.jpg&quot;:[522,522]}" style="max-width:679px;max-height:679px;">
            </div>