Can't Parse Regex : For some reason I can't parse this regex, which works in a live demonstration.

I took the code from the live demo, pasted it into a new PHP file, saved it and ran it in my server.

Works here: [live demo](https://3v4l.org/fKIqa)

My code + the error: [here](http://image.prntscr.com/image/d498412b29e8480db33bf30f68888dfb.png)

My `phpinfo`: [here](http://www.filedropper.com/temporaryphpinfo)
