# “scanning use of \frame” and “environment undefined”

I added an overlay to a frame and my beamer file started giving my trouble with the two frames that I cut and paste below. More precisely:

If I let the two frames in the text and compile, the error is "file ended while scanning use of \frame" If I take out only the second frame, it happen the same. If I take out only the first frame, the mistake is "environment undefined", and the line number corresponding to the last line of the second frame shows up.

I really don't know what to do. I am not a very skilful beamer/latex guy, but the frames are very basic, and I can't see any mistake in them.

If you have time to help me out, I would be forever grateful.

\documentclass[xcolor=dvipsnames]{beamer}

\usepackage{colourchange}
\mode<presentation> {
\usetheme{Dresden}
}

\usepackage{graphicx}
\usepackage{booktabs}

\begin{document}

\begin{frame}%[<+->]
\frametitle{How do Experience and Metaphysics relate to each other?}

\begin{itemize}

\item<2-> Experience does not distinguish between the A- and the B-theory
\item<3-> Experience is \textit{compatible} with the A-theory, the B-theory\ldots
\item<4-> \ldots Berkelyan idealism, Cartesian skeptics, Russellian skeptics\ldots
\item<5-> \ldots Hyper-Russellian skeptics:

\begin<itemize>
\item<6->{only one conscious experience exists (and it is indistinguishable from \textit{this} experience that \textit{you} are having \textit{now})
\end{itemize}

\item<7-> Yet, it does not follow that experience cannot support better a metaphysical theory over a competing one: \only<9->{All your experiences exists \textit{vs.} hyper-Russellian skeptics}

\end{itemize}

\end{frame}

%------------------------------------------------
%------------------------------------------------

\begin{frame}%[<+->]
\frametitle{An Abductive Argument for the A-theory}

\begin<itemize>
\item<2-> Different claim: Experience \textit{better supports} the A-theory''

\begin{enumerate}
\item<3-> Our experience has $E_T$
\item<4-> The thesis $A_1$ that the passage of time is an objective, mind-independent fact is an essential part of our best explanation of why our experience has $E_T$
\item<5-> \textbf{The A-theory is true}
\end{enumerate}

\end{itemize}

\end{frame}

\end{document}

• Welcome to TeX.SX! A new Italian fellow, hurray! Please, add some code to make the example compilable. – egreg Nov 13 '14 at 0:08
• To compile, it needs to start with documentclass and end with \end{document}. I can't compile frames on their own... ;) – cfr Nov 13 '14 at 0:19
• Thanks. I added it by editing the post, although I did not manage to get it inside the code window. Sorry. – Giuliano from Italy Nov 13 '14 at 0:19
• Oops. Sorry. Missed the bits outside the frame. – cfr Nov 13 '14 at 0:19
• I was adding them while you were writing, I guess :) – Giuliano from Italy Nov 13 '14 at 0:20

Localizing errors in a beamer document can be hard, because a missing brace is usually caught too late.

It helps having a “galley” document with the same preamble as the main one, where one frame is prepared at a time, then pasted to the main one when it compiles properly.

In your case you have a missing brace:

\begin<itemize>
\item<6->{only one conscious experience exists (and it is indistinguishable from \textit{this} experience that \textit{you} are having \textit{now})
\end{itemize}


should be

\begin<itemize>
\item<6->{only one conscious experience exists (and it is indistinguishable from \textit{this} experience that \textit{you} are having \textit{now})}
\end{itemize}


You also have two typos:

\begin<itemize>


should of course be

\begin{itemize}


(two places).