I was following along on this post Reading PDF content with itextsharp dll in VB.NET or C# and got red underlines at "StringBuilder" and "Encoding". I have all of the included libraries that were in the answer of the post and ItextSharp.xtra and Itextsharp.pdfa (just to see if one of them fixed the issue), but nothing that I add seems to recognize "StringBuilder" or "Encoding".
What am I doing wrong here?