I make a regtangular with a gradient, I whant to make it a patter by selecting object to pattern. The result: my original rectangular disappears, the pattern is apparently saved with a code, but when I tried to use it doesn't appear. I tried the same with an image and still not working.
Anyone? any idea? I don't know where to start cheking....
thanks and sorry for my english... =)

Could you upload the file for us to examine?
I don't have any problems when I follow your same steps (rectangle, gradient fill, Object to Pattern). The rect does not disappear.

If you can upload it either to the forum, or to petaIMG(both free) then I will be able to open it and look at it. I don't know if I will be able to solve your problem. But I haven't had much luck opening SVGs from other hosts.