Hi,
The D-Link DBT-120 Bluetooth 2.0 is not compatible with Windows 7. For more details refer to the link provided below.
In this case I would suggest you to download the drivers for Windows Vista for the D-Link DBT-120 Bluetooth 2.0 and then install the drivers in Windows Vista compatible mode on your windows 7 system.
Step 1:
Download the drivers for Windows Vista for the device from the below link
http://www.dlink.com/products/?tab=3&pid=DBT-120&rev=DBT-120
Step 2:
Once you install the drivers run the installation in compatible mode and install the drivers and check if you are able to connect the device.
To run programs in compatible mode refer to the link provided below.
http://windows.microsoft.com/en-US/windows7/Make-older-programs-run-in-this-version-of-Windows
Reference:
For more information on the D-Link DBT-120 Bluetooth 2.0 device refer to the link provided below.
http://www.dlink.com/products/?pid=DBT-120
Note:
Using Third Party Software or Link, including hardware drivers can cause serious problems that may prevent your computer from booting properly. Microsoft cannot guarantee that any problems resulting from the use of Third Party Software or Link can be solved. Using Third Party Software or Link is at your own risk.
Hope it helps!