Getting a 403 forbidden error when posting in Facebook using Prime31 pkugin from Unity3d

Getting a 403 forbidden error when posting in Facebook using Prime31
pkugin from Unity3d

Before I ask my question here are a few details of my setup and the
problem I am facing. This is my first post on StackOverflow :).
Platform : Unity3d engine + Prime31 plugin for Facebook
Context : I am trying to integrate Facebook into our Mobile iOS app,
developed using Unity3d (still in development), and I am trying to post to
the user's friend's wall using a plugin called Prime31.
Problem : I keep getting a 403 forbidden error when I post to the friends
wall
Code : I am using the following piece of code
var token = FacebookBinding.getAccessToken();
Debug.Log( "access token: " + token );
var param = new Dictionary<string,object>
{
{"message", "Test message for dragons "},
{"access_token" , token},
{"name", "School of Dragons"},
{"caption", "Join the world of Dragons"},
};
Facebook.instance.post(id+"/feed",param, OnPostComplete);
Where id is retrieved from another piece of code.
Additional Info :
With the same setup, publishing on my own wall works. (me/feed instead of
id/feed)
The friend I am trying to post to and myself both are listed as developers
in the account for the app.
I have the the info.plist additions according to the steps provided by
Prime31.
I have done extensive googling on this problem and most of the replies
indicate a high number of posts being made from the server / app as a
possible reason.
Questions :
Is filling in the Native IOS App setting in the developer console a must
for publishing ?
Is the number of posts made by a developer application in Facebook
restricted ? Because I can post to the same friends wall with the same
content outside of the app. This seems to be the least likely scenario.
Why could this problem be happening ?
Any help would be greatly appreciated as we have a deadline approaching in
three days and this feature should be done and ready in a couple of days.
Thanks Anur