emacs - Indent under the previous line

Question

This is my snippent:

foo ($1)
$0

Where I activate it with indent and touch 'arg<Tab>bar' I want like this:

  foo (x)
  bar

But I got this:

  foo (x)
bar

My yas-indent-line is fixed. Emacs 24.2.1 Yasnippet 0.8.0 (20130218)