TweetSharp and Medium Trust issues - looking for help

Question

Asp.net web application is complaining "That assembly does not allow partially trusted callers."

I am hosting with medium trust. How can I avoid this? thx

InnerException: null
Message: "That assembly does not allow partially trusted callers."
Source: "TweetSharp.Twitter"
StackTrace: "   at TweetSharp.Twitter.Fluent.FluentTwitter..ctor(IClientInfo clientInfo)\r\n   at TweetSharp.Twitter.Fluent.FluentTwitter.CreateRequest()\r\n   at TwitterLib.MyTwitter.GetRequestToken()\r\n   at TwitterLib.MyTwitter..ctor(String userName, String password)\r\n   at Controls.Twitter.GetTimeLine()\r\n   at Controls.Twitter.RenderControl(HtmlTextWriter writer)"
TargetSite: {Void .ctor(TweetSharp.IClientInfo)}