ESXI 4.1 not Recognizing New USB Devices

We have a USB hard drive dock connected to our physical server that we use for nightly backups from virtual machines. Last week I noticed that even though I had swapped to a different hard drive, it still registered the old one, and our backup had failed. I checked the cables, removed the usb device from the virtual machine and tried to add it back. Vsphere said the operation had  been successful, but the device never showed up on the VM. I tried adding a different USB hard drive, with the same result. I tried different usb ports, I tried different VMs, I tried rebooting the VMs, rebooting the main server, and restarting the management agents, with no luck. Any ideas?
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Andrew Hancock (VMware vExpert / EE MVE^2)VMware and Virtualization ConsultantCommented:
Are you configuring it like in my EE Article

HOW TO: Add and Connect a USB Device to a Virtual Machine, hosted on VMware vSphere Hypervisor ESX 4.1 ESXi 4.1, ESXi 5.0

Now, not all USB devices are supported, and USB passthrough was never, designed to connect USB external disks for backup! USB passthrough is slow, because the USB I/O is virtualised.

A better method is to add the USB device (controller) to the VM, using VM Direct Path I/O also called PCI passthrough.

It was designed to connect USB security keys, e.g. dongles to VMs.

Now your response is going to be, well it used to work, why doesn't it now...

We will need to look at the logs, and see if the Host OS (ESXi), even detects the USB device, if it does not detect the device, the VM will not recognise it.

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