[ccnet-user] install package security problem

[Edwin]

I face a problem when I use dashboard administration to install
package using ccnet1.5 released version
it throws IO Exception System.UnauthorizedAccess Exception can not
access D:\Program Files\CruiseControl.NET\webdashboard\packages
\packages.xml
I run services with administrators groups account and use default
administrator account to login dashboard administration
is there anything I should set up before I install package?Thanks