SQL/LINQ调试帮助

以下语句有问题,返回错误“sequence contains no elements”:

var vUser = (from u in this.dcLAUNCHOnline.aspnet_Users
                             where u.UserName.Equals(this.wCreateUser.UserName)
                             select u).Single();

正在生成的SQL:

SELECT [t0].[ApplicationId],
 [t0].[UserId],
 [t0].[UserName],
 [t0].[LoweredUserName],
 [t0].[MobileAlias],
 [t0].[IsAnonymous],
 [t0].[LastActivityDate],
 [t0].[FirstName],
 [t0].[LastName],
 [t0].[Address_Street],
 [t0].[Address_City],
 [t0].[Address_Province],
 [t0].[Address_Country],
 [t0].[Address_PostalCode],
 [t0].[Telephone_Main_AreaCode],
 [t0].[Telephone_Main_Prefix],
 [t0].[Telephone_Main_LineNumber],
 [t0].[Telephone_Main_Extension],
 [t0].[Telephone_Mobile_AreaCode],
 [t0].[Telephone_Mobile_Prefix],
 [t0].[Telephone_Mobile_LineNumber],
 [t0].[Telephone_Mobile_Extension],
 [t0].[Telephone_Other_AreaCode],
 [t0].[Telephone_Other_Prefix],
 [t0].[Telephone_Other_LineNumber],
 [t0].[Telephone_Other_Extension],
 [t0].[Gender],
 [t0].[BirthDate]
FROM [dbo].[aspnet_Users] AS [t0]
WHERE [t0].[UserName] = @p0
-- @p0: Input NVarChar (Size = 20; Prec = 0; Scale = 0) [six.string@gmail.com]
-- Context: SqlProvider(Sql2008) Model: AttributedMetaModel Build: 3.5.30729.4918

在SQL Server Management Studio中运行时,脚本不会返回我期望的行(在表中)

我用这行定义了p0:

DECLARE @p0 NVarChar(20) = 'six.string@gmail.com'

你知道为什么会失败吗?谢谢!