New Post: Unauthorized

I replaced the line but i keep getting the same error. But when debugging, I notice that token variable has a property with an Exception.
The property is ServerDateTimeOfPreviousRequest and the exception is :

Message = "You cannot access the server datetime before performing any HttpRequest"

The StackTrace said:
StackTrace = " at TwitterToken.Token.get_ServerDateTimeOfPreviousRequest() in c:\Users\Thomas\Documents\Tweetinvi\Release\TwitterToken\Token.cs:line 39"

Maybe thats the problem?