Thank you Walter for the workaround
Walter's approach does not work as you expect. Filters must be specified before matrix parameters. If the filter is specified after a matrix parameter it is ignored.
The actual problem is that the .type filter requires either a placetype code or a placetype name. Since placetype names may be country- and language-specific (e.g. State is Stato in Italian), you should use placetype codes (e.g. 8 for State/Stato) when you don't know the correct placetype name in the requested language and country.
Try the following code:
CODE
http://where.yahooapis.com/v1/place/23424977/children.type(8);count=0?appid=xxxx&lang=it
Eddie Babcock
Yahoo! Geo Technologies