Hello,

After some time wrangling with this error, I found out what was causing the charts to not display.

The latest version of HighCharts requires a higher version of jquery rather than what's in drupal 6 and jquery update.

Initially I was using 3.0.4 and kept getting the error opacity is undefined in the console. Eventually I used 3.0.1 and it works fine.

Hopes this helps someone else.