### `\``normalsize` not defined

The LaTeX error:

>     The font size command \normalsize is not defined:
>     there is probably something wrong with the class file.

is reporting something pretty fundamental (document base font size not set up). While this can, as the message implies, be due to a broken class file, the more common cause is that you have simply forgotten to put a `\``documentclass` command in your document.

This question on the Web: http://www.tex.ac.uk/cgi-bin/texfaq2html?label=normalszmiss