[win7-64bit] How to set WheelScrollLines in .reg file

I have created a simple .reg file to modify the WheelScrollLines key. Below is my file.

Windows Registry Editor Version 5.00

[HKEY_CURRENT_USER\Control Panel\Desktop]
"WheelScrollLines"="10"

Problem is the changes do not take effect. Whenever I double click to run this .reg file, it executes all fine the wheel scroll lines in the reg file though updated to 10 but when tested on a long document file, the old value (e.g. 4) is still there. I confirmed this by going into Control Panel -> Mouse -> Wheel -> Vertical Lines = 4.

Anybody has any idea of how to make this simple .reg file work?

Thanks!!