Problem with WiFi dongle: still no connection!

Hi,

I know there are many discussions about the topic, but after many tries I still have no luck with the setup of my Raspberry WiFi dongle.

I got the official WiFi adapter (https://www.raspberrypi.org/products/usb-wifi-dongle/ ) and followed many guides about the command line configuration, like this one:

How to Setup Wi-Fi On Your Raspberry Pi via the Command Line . My Raspberry detects the wifi usb adapter and the wifi network, but I'm still not able to connect to it.

if I run ifconfig, I see:

wlan0     Link encap:Ethernet HWaddre d4:7b:b0:08:2c:49
               inet6 addr: fe80::d67b::b0ff:fe08:2c49/64 Scope:Link
               ....

This perhaps shows something wrong with the IP address?

"sudo nano /etc/network/interfaces":

# Include files from /etc/network/interfaces.d:
source-directory /etc/network/interfaces.d

auto lo
iface lo inet loopback
iface eth0 inet dhcp

allow-hotplug wlan0
#auto wlan0

iface wlan0 inet dhcp
wpa-conf /etc/wpa_supplicant/wpa_supplicant.conf
iface default inet dhcp

"sudo nano /etc/wpa_supplicant/wpa_supplicant.conf":

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1

network={
        ssid="Laser"
        psk="Laser2015"
        proto=WPA
        key_mgmt=WPA-PSK
        pairwise=TKIP
        group=TKIP WEP104 WEP40
        auth_alg=OPEN
}

I think the problem con resides on this configuration, but I changed it many times, always without success