Generate WCF [ServiceContract] from WSDL using SvcUtil: can't find Schema information

I have a .WSDL file that contains the interfaces to communicate with a service. I need to create a host that provides the functionality described in the WSDL.

This means that I have to create an Interface with a [ServiceContract], and possibly one or more classes with a [DataContract].

I thought that SvcUtil.Exe would do this for me. The help says:

svcutil.exe can generate code for service contracts, ... from metadata documents. These metadata documents can be on disk or ...

So I run SvcUtil while in the folder with the .WSDL:

SvcUtil.exe Example.Wsdl

This gives me the following error:

Error: Cannot import wsdl:portType
Detail: An exception was thrown while running a WSDL import extension:
System.ServiceModel.Description.DataContractSerializerMessageContractImporter Error: Schema with target namespace 'http://logius.nl/digipoort/koppelvlakservices/1.2/' could not be found.
XPath to Error Source:
//wsdl:definitions[@targetNamespace = 'http://logius.nl/digipoort/wus/2.0/afleverservice/1.2/'] /wsdl:portType[@name='AfleverService_V1_2']

I interpret this as that file example.wsdl needs a schema that cannot be found.

In file Example.WSDL:

<wsdl:types>
  <xsd:schema elementFormDefault="qualified" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <xsd:import 
      namespace = "http://logius.nl/digipoort/koppelvlakservices/1.2/"
      schemaLocation="../digipoort-koppelvlak-1.2.xsd"
      />
  </xsd:schema> 
</wsdl:types>

I guess this means that the file with the requested schema should be in the super-folder with filename digipoort-koppelvlak-1.2.xsd I have a base folder that contains schema information and a subfolder that contains the .WSDL:

basefolder
    digipoort-koppelvlak-1.2.xsd
basefolder\subfolder
    Example.WSDL

The first line of digipoort-koppelvlak-1.2.xsd:

<xsd:schema xmlns:xsd = "http://www.w3.org/2001/XMLSchema"
            xmlns:tns ="http://logius.nl/digipoort/koppelvlakservices/1.2/"
            targetNamespace = "http://logius.nl/digipoort/koppelvlakservices/1.2/" 
            elementFormDefault="qualified">

This seems to me the requested schema. So why can't SvcUtil find the Schema with the mentioned namespace?

The strange thing is, that the .WSDL file seems correct, because I can create client classes for this in visual studio (menu: project / add service reference). But I don't know how to create the classes to host the service

A solution is to mention the .XSD file in the command line:

SvcUtil.exe c:\...basefolder\digipoort-koppelvlak-1.2.xsd Example.Wsdl

Although this does not explain why the XSD is not included automatically, it generates a file with the requested [servicecontract]