DWA-140 does not work on Ubuntu 10.04

I have just installed the Ubuntu 10.04 and I have a wireless interface through the DWA-140 DLink and a the DIR-635 wireless router also from DLink.
When the router is configured as 11n my network is not found. When I configyred as 11g the network is found but I cannot connect.
If someone can help me see below some command results. Thanks.

ifconfig:

eth0 Link encap:Ethernet Endereço de HW 00:1d:92:bc:41:cf
          UP BROADCAST MULTICAST MTU:1500 Métrica:1
          pacotes RX:0 erros:0 descartados:0 excesso:0 quadro:0
          Pacotes TX:0 erros:0 descartados:0 excesso:0 portadora:0
          colisões:0 txqueuelen:1000
          RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)
          IRQ:28 Endereço de E/S:0xa000

lo Link encap:Loopback Local
          inet end.: 127.0.0.1 Masc:255.0.0.0
          endereço inet6: ::1/128 Escopo:Máquina
          UP LOOPBACK RUNNING MTU:16436 Métrica:1
          pacotes RX:88 erros:0 descartados:0 excesso:0 quadro:0
          Pacotes TX:88 erros:0 descartados:0 excesso:0 portadora:0
          colisões:0 txqueuelen:0
          RX bytes:6560 (6.5 KB) TX bytes:6560 (6.5 KB)

wlan0 Link encap:Ethernet Endereço de HW 00:1c:f0:99:ba:d8
          UP BROADCAST MULTICAST MTU:1500 Métrica:1
          pacotes RX:0 erros:0 descartados:0 excesso:0 quadro:0
          Pacotes TX:0 erros:0 descartados:0 excesso:0 portadora:0
          colisões:0 txqueuelen:1000
          RX bytes:0 (0.0 B) TX bytes:0 (0.0 B)

iwconfig:

wlan0 IEEE 802.11bgn ESSID:off/any
          Mode:Managed Access Point: Not-Associated Tx-Power=5 dBm
          Retry long limit:7 RTS thr:off Fragment thr:off
          Power Management:on

sudo lshw -C network:

  *-network
       description: Ethernet interface
       product: MCP73 Ethernet
       vendor: nVidia Corporation
       physical id: f
       bus info: pci@0000:00:0f.0
       logical name: eth0
       version: a2
       serial: 00:1d:92:bc:41:cf
       capacity: 100MB/s
       width: 32 bits
       clock: 66MHz
       capabilities: pm msi bus_master cap_list ethernet physical mii 10bt 10bt-fd 100bt 100bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=forcedeth driverversion=0.64 latency=0 link=no maxlatency=20 mingnt=1 multicast=yes port=MII
       resources: irq:28 memory:feb77000-feb77fff ioport:c880(size=8) memory:feb7e800-feb7e8ff memory:feb7e400-feb7e40f
  *-network
       description: Wireless interface
       physical id: 1
       logical name: wlan0
       serial: 00:1c:f0:99:ba:d8
       capabilities: ethernet physical wireless
       configuration: broadcast=yes multicast=yes wireless=IEEE 802.11bgn

lsusb:

Bus 002 Device 002: ID 0ac8:0302 Z-Star Microelectronics Corp. ZC0302 Webcam
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
Bus 001 Device 004: ID 058f:6366 Alcor Micro Corp. Multi Flash Reader
Bus 001 Device 002: ID 07d1:3c09 D-Link System DWA-140 802.11n Adapter [ralink rt2870]
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub