Commented Unassigned: Unable to publish in reply to [2554]

I had the above mentioned working before and all of a sudden it has stopped. My code for replying to the tweet is as follows:

var newTweet = Tweet.CreateTweet(message);
var result = newTweet.PublishInReplyTo(tweetId);

The result is returned as false. Is there a way to figure out why?
Comments: ** Comment from web user: iserialize **

Havent tried that. Is it the Twitter Access Credentials or the Twitter Consumer Credentials? Is there an event that can be subscribed to that advises that the credentials need changing or is it something that needs to be done whenever i strike the above mentioned issues.

Thanks for the assistance.