找不到配置绑定扩展

“找不到配置绑定扩展名'system.serviceModel/bindings/webHttpBinding'。请验证此绑定扩展名是否在system.serviceModel/extensions/bindingExtensions中正确注册,以及拼写是否正确。”

我想我错过了一些非常基本的步骤。有人能帮我吗?

<service name="WebService.Service1">
  <endpoint address="" binding="webHttpBinding" contract="WebService.IService1" behaviorConfiguration="RestBehavior" />
</service>

<endpointBehaviors>
  <behavior name="RestBehavior">
    <webHttp />
  </behavior>
</endpointBehaviors>