c# – WCF数据服务：尽管服务设置为v3,但MaxProtocolVersion设置

public class TestDirectorySearch : DataService<TestDirectoryEntities>
{
    public static void InitializeService(DataServiceConfiguration config)
    {
        config.SetEntitySetAccessRule("*",EntitySetRights.AllRead);
        config.SetEntitySetPageSize("*",50);

        config.UseVerboseErrors = true;
        config.DataServiceBehavior.MaxProtocolVersion = System.Data.Services.Common.DataServiceProtocolVersion.V3;
    }
}

我的edmx有以下几行：

<edmx:DataServices m:DataServiceVersion="1.0" 
    m:MaxDataServiceVersion="3.0" 
    xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">

当我尝试执行以下查询时,指出当MaxProtocolVersion小于’3.0’时,不支持“方法’OfType’.”

from test in context.Tests.OfType<OrderableTest>()
    where test.TestRevisionId.Equals(mmt.RevisionId)
    select new
    {
            Reflex = test.ReflexTest,ShipTemp = (test.SpecimenTemperature == null) ? null : test.SpecimenTemperature.DisplayDescription
    }).FirstOrDefault();

如果我检查上下文的MaxProtocolVersion,则将其设置为v2.在什么时候失败了？我该怎么做才能正确设置？

确切的错误：

{“当MaxProtocolVersion小于’3.0’时,不支持’OfType’方法.”}

请求的堆栈跟踪：

at System.Data.Services.Client.ResourceBinder.AnalyzeOfType(MethodCallExpression mce,DataServiceProtocolVersion maxProtocolVersion)
at System.Data.Services.Client.ResourceBinder.VisitMethodCall(MethodCallExpression mce)
at System.Data.Services.Client.ALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.DataServiceALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.ALinqExpressionVisitor.VisitExpressionList(ReadOnlyCollection`1 original)
at System.Data.Services.Client.ALinqExpressionVisitor.VisitMethodCall(MethodCallExpression m)
at System.Data.Services.Client.ResourceBinder.VisitMethodCall(MethodCallExpression mce)
at System.Data.Services.Client.ALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.DataServiceALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.ResourceBinder.AnalyzeProjection(MethodCallExpression mce,SequenceMethod sequenceMethod,Expression& e)
at System.Data.Services.Client.ResourceBinder.VisitMethodCall(MethodCallExpression mce)
at System.Data.Services.Client.ALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.DataServiceALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.ALinqExpressionVisitor.VisitExpressionList(ReadOnlyCollection`1 original)
at System.Data.Services.Client.ALinqExpressionVisitor.VisitMethodCall(MethodCallExpression m)
at System.Data.Services.Client.ResourceBinder.VisitMethodCall(MethodCallExpression mce)
at System.Data.Services.Client.ALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.DataServiceALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.ResourceBinder.Bind(Expression e,DataServiceContext context)
at System.Data.Services.Client.DataServiceQueryProvider.Translate(Expression e)
at System.Data.Services.Client.DataServiceQuery`1.Translate()
at System.Data.Services.Client.DataServiceQuery`1.Execute()
at System.Data.Services.Client.DataServiceQuery`1.GetEnumerator()
at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source)
at System.Data.Services.Client.DataServiceQueryProvider.ReturnSingleton[TElement](Expression expression)
at System.Data.Services.Client.DataServiceQueryProvider.Execute[TResult](Expression expression)
at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source)
at TDMixBLL.TestDirectoryServiceHandler.PopulateOrderableTestInfo(MonitoredMixTest mmt) in C:DevTDMixANSR - TDMixTDMix2TDMixBLLTDMixBLLTestDirectoryServiceHandler.cs:line 161
at TDMixBLL.TestDirectoryServiceHandler.PopulateTestInfo(MonitoredMixTest test) in C:DevTDMixANSR - TDMixTDMix2TDMixBLLTDMixBLLTestDirectoryServiceHandler.cs:line 124
at TDMixBLL.TestDirectoryServiceHandler.GetTest(Int64 testRevisionId) in C:DevTDMixANSR - TDMixTDMix2TDMixBLLTDMixBLLTestDirectoryServiceHandler.cs:line 112
at TDMixBLL.TestDirectoryServiceHandler.PopulateTests(List`1 testsToPopulate) in C:DevTDMixANSR - TDMixTDMix2TDMixBLLTDMixBLLTestDirectoryServiceHandler.cs:line 66
at TDMix2.Tests.TestRetrievalTests.TestPopulate() in C:DevTDMixANSR - TDMixTDMix2TDMix2.TestsTestRetrievalTests.cs:line 38