为什么我的LINQ to SQL查询第一次失败（“未找到或未更改行”）并第二次成功？

I'm using LINQ to SQL in ASP.NET MVC. I wrote some new code to update Orders in our system, and as far as I can tell it's exactly like a hundred other similar pieces of code I've written (grab the object, update some fields, submit changes).I'm using LINQ to SQL in ASP.NET MVC. I wrote s