System.IdentityModel.Selectors.UserNamePasswordValidator does not exist [closed]

Question

I am trying to derive a class from System.IdentityModel.Selectors.UserNamePasswordValidator. However if I add a reference to System.IdentityModel.Selectors I still can't add System.IdentityModel.Selectors.UserNamePasswordValidator as it tells me it does not exist in the namespace. Microsofts own documentation says it is in there and there are many examples on the web using this class, however it just refuses to recognise it on my machine......

Answer 1

I have found the issue. I needed to also add a reference to System.IdentityModel.