First let me begin with the tutorial. It starts with:
The basic syntax for a graph is as follows:
{graph="type:1;"}{bar="barsize:50%"}{/graph}
this should be:
{graph="type:1;"}{bar="barsize:50%;"}{/graph}
Note the ; after the barsize. I guess this will help most users to get it up and running.
I must say the plugin works quite nice though I was hoping for a more functional plugin that gets data out of the SQL database. For the general use it is a nice and lean plugin that does the job right.