How do I add an action to post to my Facebook wall?

I use the Facebook SDK for .NET and I can post it to the user wall using an app token.

Code example where I create the post:

        dynamic messagePost = new ExpandoObject();
        messagePost.picture = "http://cs608830..........jpg";
        messagePost.name = "A.......";
        messagePost.message = "I........ ";
        messagePost.link = "http://a.......";
        messagePost.req_perms = "publish_stream";
        messagePost.scope = "publish_stream";
        messagePost.actions =
            "[{\"name\": \"View on .....\",\"link\": \"https://play.google.com/store/apps/details?id=com.........\"}]";
        messagePost.privacy = new
        {
            value = "SELF"
        };

Its a good post, but I want to add a second action:

   messagePost.actions =
            "[{\"name\": \"View on Play Market\",\"link\": \"https://play.google.com/store/apps/details?id=com.....\"},
              {\"name\": \"View on iTunes \",\"link\": \"https://itunes.apple.com/us/app/sla......\"}  ]";

However, when I add the secon action, I get the next error:

 (OAuthException - #100) (#100) actions should be a JSON-encoded dictionary with "name" and "link" keys

I can definitely add a second action, because in the documentation https://developers.facebook.com/docs/reference/api/post/ I see the next one: Actions - List of actions available in the post (including comments , likes, and optional app-specific actions) So what am I doing wrong?