Missing argument 2 for open_flash_chart_api_help() warning

It looks like your implementation of hook_help makes reference to a 2nd parameter ($arg) that isn't used and has no value when the function is called. If Drupal reports PHP warnings, you'll receive this error on installation of the module. Switching the declaration of the function to:

function open_flash_chart_api_help($path) {
...
}

will remedy this problem.