Opal Dream (2006)

Pobby and Dingan live in the opal capitol of Australia. They are friends with Kellyanne Williamson, the daughter of a miner - but only Kellyanne can see them. Pobby and Dingan are imaginary. Kellyanne's brother Ashmol, thinks his sister should grow up and stop being such a fruit-loop - until the day when Pobby and Dingan disappear, the same day that his father is accused of ratting, the worst sin an opal miner can commit. As Kellyanne, grief-stricken, begins to fade away, Ashmol recruits the whole town in the search for Pobby and Dingan.

Official website: http://www.iconmovies.com.au/opaldream