Problem with @Diag

[Ludo']

Hi,

I am currently trying to represent a finite state automata (FSA)
using the diag package. I'd like at some point to have one state
linked to itself with a curved arrow. I tried an @Link from { Q0 }
to { Q0 } but it doesn't work.

Any idea of how I could do such a thing?

Thanks in advance for your various answers... ;)

Ludovic.