Taking ownership of system files in Vista

I have tried following the instructions exactly, to take ownership and the takeown command works with "SUCCESS..." but the icacls command does not work. My file system file I want to migrate is like this
C:Users\Wahwah\Appdata\Local\Microsoft\Windows\UsrClass.dat
so I use command prompt with

C:\Users\Wahwah\Appdata\Local\Microsoft\Windows>takeown/f UsrClass.dat [enter]
Result:
Success:the file<or folder>C:\Users\Myself\AppData\Local\Microsoft\Windows\UsrClass.dat is now owned by user "Wahwah-PC/Wahwah"

Then I put

C:\Users\Wahwah\Appdata\Local\Microsoft\Windows>icacls UsrClass.dat grant/Administrator:f[enter]
result
The system cannot find the file specified.
Sorry for the trouble, I hope someone can help me
Successfully processed 0 files, Failed processing 1 file(s)

Changing Adminstrator or "Administrators" and changing it to Wahwah and changing to an additional username result in "Invalid parameter". "Administrator:f" works the best but cannot find the file specified.

Is my syntax wrong or is the file somehow hidden or invisible? Do I need to change its permissions to 777? How is that done?

 

Hello. I found this link and this is what I have been using for the Take Ownership. I hope this is of some use.

http://www.askvg.com/add-take-ownership-option-in-file-folder-context-menu-in-windows-vista/

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