Getting access denied error for admin account in Windows Vista trying to execute CasPol command

Hi! I'm trying to execute the following command in Windows Vista under administrative account:

C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CasPol.exe -polchgprompt off -machine -ad
dgroup All_Code -strong -file myProgram.exe -noname -noversion FullTrust -name "MyProgram" -description "MyProgram Description."

However, i'm getting the following error:
ERROR: Runtime error: Access denied. You might not have administrative credentia
ls to perform this task. Contact your system administrator for assistance.

For usage information, use 'caspol -?'

Please note, that i'm logged in as an administrator. Any ideas what i need to change into the settings to get it to work? Thank you