WCF REST web服务:找不到约定名称

我正在使用WCF REST Start kit构建一个RESTFul服务。我定义了这样一个服务:

namespace MyNS {
  [ServiceBehavior(IncludeExceptionDetailInFaults = true, 
   InstanceContextMode = InstanceContextMode.Single,
   ConcurrencyMode = ConcurrencyMode.Single)]
  [AspNetCompatibilityRequirements(
   RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
  public class MyService : MyCollectionServiceBase, IMyCollectionServiceBase 
  {...}
}

MyCollectionServiceBase和IMyCollectionSeviceBase的定义如下:

namespace MyNS.Contract {
  [ServiceContract]
  public interface IMyCollectionServiceBase<TItem> where TItem : class 
  {...}

  // COllectionServiceBase is an abstract class in 
  // Microsoft.ServiceModel.Web.SpecializedServices
  public abstract class MyCollectionServiceBase<TItem> :
    CollectionServiceBase<TItem>
    where TItem : class
  {...}
}

<serviceBehaviors>
  ...
  <behavior name="MyNS.MyService1Behavior">
    <serviceMetadata httpGetEnabled="true" />
    <serviceDebug includeExceptionDetailInFaults="false" />
  </behavior>
</serviceBehaviors>
...
<service behaviorConfiguration="MyNS.MyService1Behavior"
  name="MyNS.MyService1">
  <endpoint address="" binding="wsHttpBinding" 
    contract="MyNS.IMyService1">
    <identity>
      <dns value="localhost" />
    </identity>
  </endpoint>
  <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange" />
</service>

当我测试我的服务时使用“ http://localhost:1290/MyService.svc/ “,我收到错误消息说:

The contract name 'MyNS.Contract.IMyCollectionServiceBase' could not be found 
in the list of contracts implemented by the service 'MyService'.

我不确定端点是否不匹配或缺少什么?