Output problem with specific file

[damianpab]

Im using your demo ios app to show the waves related to this file: https://drive.google.com/file/d/0B898a2Y5OUavQUZUQjNfQlFzSWM/view?usp=sharing

but the output shows the waves in a constant value.
The same file using this web audio editor https://twistedwave.com/ show the correct output

Is there any special configuration that in the demo app to change the output? Thanks