Wifi connect, no ping

Hi,

I've installed Sparky Linux rolling (=Debian Testing).
The machine uses a Planex wifi dongle based on the RTL8188SU chipset.

During installation everything went fine (connected by wifi to a hotspot).

When I login into the desktop it connects connect to the hotspot but ping fails: "Destination host unreachable".

/etc/resolv.conf:
nameserver 8.8.4.4 # added manually
nameserver 192.168.205.251

ifconfig & iwconfig show wlan0 is up and running

Any suggestions?

Thanks