I'm trying to write up all my university theorems and I cant get the theorem environment to work. Here is a mini example of what I'm trying to do.
\documentclass[a4paper,12pt]{article}
\usepackage[utf8]{inputenc}
\usepackage[english]{babel}
\usepackage{amssymb,amsmath,amsthm, amsfonts}
\newcommand{\vect}[1]{\vect{\underline{#1}}}
\newcommand{\bi}[1]{\textit{\textbf{#1}}}
\title{Theorems\\ Y3 S1}
\author{Hannahl}
\begin{document}
\maketitle
\section{Mathematical Methods}
\begin{theorem}{Placheral's Theorem}
||F||^2_2 =2\pi ||u||^2_2
\end{theorem}
\end{document}
I get this error
! LaTeX Error: Environment theorem undefined.
I am using windows 7 have MikTex 2.9 installed and am using TexMaker. From what I have read the theorem environment should be part of the amsthm package which I have. But it isn't working!
Any help will be much appreciated.