Why doesn't the C# compiler automatically infer the types in this code?

Why does the C# compiler not infer the fact that FooExt.Multiply() satisfies the signature of Functions.Apply()? I have to specify a separate delegate variable of type Func<Foo,int,int> for the code to work ... but it seems like type inference should handle this. Am I wrong? And, if so, why?

EDIT: The compilation error received is:

The type arguments for method FirstClassFunctions.Functions.Apply<T1,T2,TR>(T1, System.Func<T1,T2,TR>, T2)' cannot be inferred from the usage. Try specifying the type arguments explicitly

namespace FirstClassFunctions  {
    public class Foo  {
        public int Value { get; set; }

        public int Multiply(int j) {
            return Value*j;
        }
    }

    public static class FooExt  {
        public static int Multiply(Foo foo, int j) {
            return foo.Multiply(j);
        }
    }

    public static class Functions  {
        public static Func<TR> Apply<T1,T2,TR>( this T1 obj, 
                                                Func<T1,T2,TR> f, T2 val ) {
            return () => f(obj, val);
        }
    }


    public class Main  {
        public static void Run()  {
            var x = new Foo {Value = 10};
            // the line below won't compile ...
            var result = x.Apply(FooExt.Multiply, 5);
            // but this will:
            Func<Foo, int, int> f = FooExt.Multiply;
            var result = x.Apply(f, 5);
        }
    }