Wacom Intuos 4 wireless cannot connect via bluetooth

I am using iMac 27 with Wacom Intuos4 wireless tablet and installed both OSX 10.6.3 and Windows 7. The Tablet connection on mac platform is working fine, however, I cannot connect the tablet on Windows. I tried both driver version 6.1.3 (come with the tablet CD) and version 6.1.5-3a (download from the web), both version of drivers were failed to connect.

Here is the message prompt on the window

"Adding this device to this computer failed

Adding this device failed because of an authentication error. ... ..."

Actually, the device was detected via bluetooth but it just cannot connect in windows.