ESX 4.1 USB Passthrough - not able to add USB device

Hi guys,

Having an issue trying to get USB passthrough working on our ESX environment (v 4.1) running on IBM X Series 3360 hardware.

I've followed a few guides on the setup and have been able to add the USB controller to the guest VM but when attempting to add a USB device I receive the "There are no USB devices available on the host". I've rebooted the guest VM and can see the USB controllers in device manager (Server 2008 R2) ok but it can't detect any USB devices plugged into the host. I've tried plugging in just a thumb drive and there is a KVM plugged into the host also that has USB for the kb.

Funny thing is that it appears to be working on one of our other ESX hosts (running same host hardware and same guest and host software versions) - I get the option to choose a USB device fine.

Specifcally it's an APC Smart-UPS 2200 that we're trying to get the USB connectivity up for the monitoring functionality. Could it be an issue with the UPS not being a supported device?

Have followed a few guides same as this: https://vstorage.wordpress.com/2010/07/15/usb-passthrough-in-vsphere-4-1/#comment-45

Also saw this thread - and have confirmed we're running ESX 4.1 (as per the issues which were occurring in the thread): http://community.spiceworks.com/topic/107066-anyone-having-any-luck-with-the-new-vsphere-4-1-usb-passthrough-capability

Attached is the list of controllers that have been enabled for passthrough from the host.

Any help greatly appreciated.