MP3 audio works on iPad iOS 7.0.4, but not iPhone iOS 7.0.4. Help?

Currently working with Lectora Inspire vX.6.

When I click a button to play MP3 audio on the iPad it works fine.

When I open the same exact course on my iPhone, the audio controller bar reads "Cannot play audio file." for all pieces of audio.

Am I missing something? Both devices are running iOS 7.0.4.