unable to get HttpBrowserCapabilities to work...

Does anyone know why I'm unable to access browser properties from a class in the app_code folder?

Here's my  code:

  System.Web.HttpBrowserCapabilities Browser = new System.Web.HttpBrowserCapabilities();

string strBrowserDetails = ("Platform: " + strPlatform + "<br />Browser: " + strBrowser + " Version: " + strVersion + "<br />ActiveX: " + strActiveX + "<br />Javascript: " + strJavascript);

strPlatform = Browser.Platform.ToString();
strBrowser = Browser.Browser.ToString();
strVersion = Browser.Version.ToString();
strActiveX = Browser.ActiveXControls.ToString();
strJavascript = Browser.EcmaScriptVers ...