Files made with a newer version of a program are rarely usable with old versions of the same program. That happens with pretty much all program and is a results of new features being ... new. The old verison doesn't know how to handle the new format. It's just a way of life. It's like trying to install an new model engine inside a old style chassis. The mount points, transmission and everything else don't match :)

Paolo

https://www.preta3d.com
FB: https://www.facebook.com/RealityPlugIn
Tw: @preta3d
G+: https://plus.google.com/106625816153304163119
The Reality Gallery: https://reality-plug-in.deviantart.com