I have a Microsoft Sculpt Touch bluetooth mouse, and a bluetooth/USB dongle.

I have tried to pair with the mouse by going to System Settings > Bluetooth and clicking on the "+" button to add a device. This launches the Bluetooth New Device Setup wizard, which lists the mouse at the Device Search stage.

I can only click "Continue" on the wizard if I select a PIN option (or tell it not to use one). But I always just see:

Connecting to '(null)'...

...followed by:

Setting up '(null)' failed.

How do I connect to and use the mouse?

The dongle is listed by lsusb as:

Bus 005 Device 002: ID 0a12:0001 Cambridge Silicon Radio, Ltd Bluetooth Dongle (HCI mode)

After plugging it in, dmesg shows:

[  256.876091] usb 5-1: new full-speed USB device number 2 using uhci_hcd

[  257.132851] Bluetooth: Generic Bluetooth USB driver ver 0.6

[  257.135389] usbcore: registered new interface driver btusb

I'm using 12.04 with kernel 3.2.0-35-generic.