You might not having the right WIFI adapter driver.
Check here :-
http://support.acer-euro.com/drivers/downloads_gd.html
It has 3 different driver for the said netbook :-
Atheros, Broadcom and Realtek
OS Acer Aspire One D260, Cant enable wifi on Network Connections
Aug 30 2010, 02:23 PM
Quote
0.0147sec
0.73
7 queries
GZIP Disabled