I suggest the OP to try to connect using this command if is available as root or using sudo if that applies.
However, for the system to be able to use ifup /etc/network/interfaces must also be edited accordingly. Ironically, what helped in my peculiar case, was a defunct thread from a forlorn forum dated 2004! I changed my /etc/network/interfaces to look something like this:
# WIRELESS Configuration
iface wlan0 inet dhcp
wpa-proto WPA RSN
Hopefully, this helps you.