ESXI 4.1 doesn't "see" 10gbe NICs

Hi I've installed HP NC512m mezzanine cards in my BL685c gen1 blades,  have a 10Gb Ethernet Switch in the enclosure and the ILO manager informs me that the adapters are mapped on the switch. All is good so far, the VMWARE HCL tells me that the nc512m is compatible with esxi 4.1u2 . I have a custom HP image with the driver installed :

/tmp # ipkg list_installed | grep nx-nic

vmware-esx-drivers-net-nx-nic - 400.4.0.550.1-2vmw.2.11.502767 -

I can see the devices :

~ # lspci | grep NetXen

000:068:00.0 Network controller: NetXen XG Mgmt

000:068:00.2 Network controller: NetXen NC512m Dual Port 10GbE Multifunction BL-C Adapter [vmnic8]

000:068:00.3 Network controller: NetXen NC512m Dual Port 10GbE Multifunction BL-C Adapter [vmnic9]

But the NICs aren't visible in the VSphere Client.

~ # esxcfg-nics -l

Name    PCI           Driver      Link Speed     Duplex MAC Address       MTU                                 Description

vmnic4  0000:03:00.00 bnx2        Up   1000Mbps  Full   00:19:bb:3b:cf:20 1500                                Broadcom Corporation NC373i Integrated Multifunction Gigabit Server Adapter

vmnic5  0000:05:00.00 bnx2        Up   1000Mbps  Full   00:19:bb:3b:cf:16 1500                                Broadcom Corporation NC373i Integrated Multifunction Gigabit Server Adapter

vmnic6  0000:07:04.00 tg3         Up   1000Mbps  Full   00:19:bb:3b:7c:dd 1500                                Broadcom Corporation NC326i PCIe Dual Port Gigabit Server Adapter

vmnic7  0000:07:04.01 tg3         Up   1000Mbps  Full   00:19:bb:3b:7c:de 1500                                Broadcom Corporation NC326i PCIe Dual Port Gigabit Server Adapter

~ #

Any idea on how to enable them and use them ?

Thanks in advance.