WCF validating service certificate using a custom validator on the client side

Question

If I am using a custom validator to validate the service certificate on the client side, what do i need to do? so far I have the following:

1. Implemented my own custom validator to validate which implemnents X509CertificateValidator.
2. Configure the app.config for the client to use the endpointbehavior where I specify to use the Custom Validator.
3. After an instance of the service client is created, I set to use my own custom validator as follows: client.ClientCredentials.ServiceCertificate.Authentication.CertificateValidaionMode = Security.X509CertificateValidatioinMode.Custom; client.ClientCredentials.ServiceCertificate.Authentication.CertificateValidaionMode = new MyCertificateValidator().

I am not sure if the step 3 is need or not(how do I tell to use custom validator when validating the service certificate).

For this setup, I have an error type load error when running the client (it failed to load my custom validator). I am missing something. Also, where do I put the custom validator class: in the client or in the service?