Error 400 : invalid request on httpwebrequest

Question

I've built a WCF service that is hosted on a server by a windows service. Everything works fine and i have already tested some method. Now i need to send an httprequest from my client like this one:

 HttpWebRequest req = (HttpWebRequest)WebRequest.Create(String.Format(@"http://192.168.0.170:9001/myServ/Start/{0}/{1}", "blabla", "blabla"));
 req.Method = "GET";

The problem is that i keep getting an exception on client side stating that my request is invalid. I can't understand why.

This is my wcf service:

[OperationContract]
[WebInvoke(Method = "GET",
 UriTemplate = "Start/{param1}/{param2}")]
 string Mod(string param1, string param2);

Here is my configuration

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <appSettings>
    <add key="aspnet:UseTaskFriendlySynchronizationContext" value="true"/>
  </appSettings>
  <system.web>
    <compilation debug="true"/>
  </system.web>
  <!-- When deploying the service library project, the content of the config file must be added to the host's 
  app.config file. System.Configuration does not support config files for libraries. -->
  <system.serviceModel>
    <bindings>
      <webHttpBinding>
        <binding maxBufferSize="2147483647"
                 maxBufferPoolSize="2147483647"
                 maxReceivedMessageSize="2147483647"
                 transferMode="Streamed"
                 sendTimeout="00:05:00"
                 name="WebHttpBinding_InotifyImp">
          <readerQuotas  maxDepth="2147483647"
                         maxStringContentLength="2147483647"
                         maxArrayLength="2147483647"
                         maxBytesPerRead="2147483647"
                         maxNameTableCharCount="2147483647"/>
          <security mode="None" />
        </binding>
      </webHttpBinding>
    </bindings>
    <services>
      <service name="wcfImp.notifyImp" behaviorConfiguration="NewBehavior">
        <endpoint address="" behaviorConfiguration="DefaultEndPointBehavior" bindingConfiguration="WebHttpBinding_InotifyImp" binding="webHttpBinding" contract="wcfImp.InotifyImp">
          <identity>
            <dns value="localhost"/>
          </identity>
        </endpoint>
        <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
        <host>
          <baseAddresses>
            <add baseAddress="http://localhost:9001/notifyImp"/>
          </baseAddresses>
        </host>
      </service>
    </services>
    <behaviors>
      <serviceBehaviors>
        <behavior  name="NewBehavior">
          <!-- To avoid disclosing metadata information, 
          set the values below to false before deployment -->
          <serviceMetadata httpGetEnabled="True" httpsGetEnabled="True"/>
          <!-- To receive exception details in faults for debugging purposes, 
          set the value below to true.  Set to false before deployment 
          to avoid disclosing exception information -->
          <serviceDebug includeExceptionDetailInFaults="True"/>
        </behavior>
      </serviceBehaviors>
      <endpointBehaviors>
        <behavior name="DefaultEndPointBehavior">
          <webHttp helpEnabled="true" />
        </behavior>
      </endpointBehaviors>
    </behaviors>
  </system.serviceModel>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6.1"/>
  </startup>
</configuration>

Answer 1

I found the problem. I was hosting my WCF service in debug mode using visual studio 2015 to check the various step of my process. I don't know why, but while i didn't have any problem with the other method, the handler associated to the get method, have an assembly that couldn't be loaded. I tried to host the service on windows service and everything worked fine