[jdom-interest] problems with "indent"

[NP]

Hi!
I have to indent my xml document, so i write:

XMLOutputter serializer = new XMLOutputter();
serializer.getFormat().setIndent("   ");
serializer.getFormat().setLineSeparator("\n");
....
serializer.output(doc, fout); //doc is a Document's obj, fout is a 
FileOutputStream

1. but it doesn't work..
2. i have some problems also using the XMLOutputter(Format) constructor: 
why i can't create a Format obj?

thanks!