how to access property of class in F#

Question

type IMyInterface= interface
    abstract MyProperty : int with get,set  
  end

  type MyClass() =
    let mutable x :int = 0
    interface IMyInterface with
       member this.MyProperty with get()= x
       member this.MyProperty with set(value)=x<-value

I am trying to access MyProperty using MyClass object but I am not able to access this property. means that,

let obj=new MyClass();
obj.MyProperty=...; // **MyProperty** is not showing  in F#

(object Of Myclass).Myproperty is not showing.