Rob,

You have no idea of how much help you have been! Thanks a lot man! I´m sure I´ll be able to fix it somehow!! Thanks for the explanation probably is not recognizing it, I´ll try to find a solution!

Take care,

Roberto

I want to say splines are not supported, but my memory is fading more and more every day. 

If you save as version 12, splines are automatically converted to polylines when using AutoCAD.