Recurly.js and Angular 4

I'm using an angular reactive form and trying to get a token from Recurly.js.

I've used the recurly suggested name for the input and added the data-recurly="number" for the cc number and so on.

On submit first I call recurly.configure() and then I take the value from the reactive form and pass it to recurly.token() in this way:

recurly.token(this.form.value, function (err, token) {
    if (err) {
      // handle error using err.code and err.fields
      console.log("Recurly token error: " + err);
    } else {
      // handle success using token.id
      console.log("Recurly token success: " + token.id);
    }
  });

this.form.value contains the correct field names and values but I always get the following validation error:

Am I missing something?

Thanks, Dem