TypeError: Raphael is not a function

hello, I got this error **sometime** when I using flowchart.js, it's gone when refresh the page 4~5 times.

when I do `console.log(Raphael)` before initialize flowchart.js got:

```
function Your browser supports SVG.
You are running Raphaël 2.1.0
```

`raphael-min.js` and `flowchart.js` is asyn loaded by jquery.

any help?

thanks!