Problem with boolean modifier

Hi Everybody!
That’s my first post in this forum, and I am beginner in Blender.
I don´t know how to do a good boolean operation with the option difference in blender. When I use normal mesh, like sphere or cube, it all right, but I had two objects from Bezier Curves and used the command ALT + C (to convert from curves to mesh) each Curve object, and the boolean modifier make the “diference” only in the faces, like if the mesh were not solid.
Should I do something with the both mesh before I apply the Boolean modifier?
I send the fotos, because my English is really bad, sorry!

Thanks :wink:

Make sure before using boolean that you have removed all double vertices (select all vertices and W / remove doubles) and your face normals are consistant. Recalculate normals by selecting all faces and Ctrl+N

Thank you very much!
I did what you say in your anwser and i had become that…

The object “decoration” have I in another layer

Maybe I made something else wrong, I´ll try it again in another proyect :frowning: