Transparent Adobe Animation file

It may be a stupid question - but I don't know the answer, so...
is there a way to export an Adobe Animation file so the background is transparent and can then be imported into Storyline 360 to be used as an overlay on a slide?

Here is what I am trying to accomplish

• Character is animated with audio (currently exporting to mov or mp4 file)
• Want to overlay the character onto an existing scene/image in Storyline. E.g. the character will walk across the screen with various backgrounds that exist on lower layers of a Storyline slide.
• I do not want to have to create animations with background scenes - I want to reuse the character animation on several different slides with changing backgrounds.

Problem I can't resolve - the character background is showing up as Black, so you can't see what is under that area of the slide.

Any suggestions on how to easily resolve this?

Thanks for any assistance that may help resolve this problem.