In order to establish why your version is not working, we need to see the exact code you are using. Linking to a working example does not help us determine where the problem lies with your own version.
If the demo is working, and your version is not, then there must be some reason for that. Perhaps it’s a simple copy & paste error. Maybe you’ve forgotten to link to a required resource, or the path name is incorrect.
Without seeing your code, we have no way of knowing where the problem lies, so you’ll need to check these things very carefully for yourself.