I'm trying to learn how to use PGF/TikZ to draw pictures, in particular a chain of nodes.

I have the following picture:

```
\begin{tikzpicture}[start chain, node distance=5mm]
\node [on chain,join] {$t_\mathrm{opt flow}$};
\node [on chain,join] {$foo$};
\end{tikzpicture}
```

I would expect this to yield two nodes connected by a simple

line. Instead, when I run LaTex, I get the following error:

```
./NIQ_Principles.tex:39: Package PGF Math Error: Unknown function `of'.
./NIQ_Principles.tex:40: Extra }, or forgotten \endgroup.\endpgfpicture ... \pgf@y }\endgroup \hss \egroup
\pgf@insertlayers \endgrou...
```

Can someone help me understand what I'm doing wrong?

**UPDATE**

Here is my complete example:

```
\documentclass{scrartcl}
\usepackage{tikz}
\usetikzlibrary{chains}
\begin{document}
\begin{tikzpicture} [start chain, node distance=5mm]
\node [on chain,join] {foo};
\node [on chain,join] {bar};
\end{tikzpicture}
\end{document}
```

And here is the output I get:

```
ERROR: Package PGF Math Error: Unknown function `of'.
--- TeX said ---
See the PGF Math package documentation for explanation.
Type H <return> for immediate help.
...
l.10 \node [on chain,join]
{bar};
--- HELP ---
From the .log file...
This error message was generated by an \errmessage
command, so I can't give any explicit help.
Pretend that you're Hercule Poirot: Examine all clues,
and deduce the truth by order and method.
```

I can't really claim that I'm as smart as Mr Poirot, so can someone

point me in the right direction?

## Best Answer

I found that the

`pgf`

package installed under Ubuntu was version 2.00, whereas the latest version (and the one from whose documentation I was trying the examples) was 2.10.Installing the latest version of

`pgf`

under my local`texmf`

tree solved the problem.