Parental Control Problems

I'm trying to set parental controls on my standard user accounts. I am the administrator. When I click on the account, a dialogue box pops up and says "Unable to make changes to parental control settings, if this problem persists contact your system administrator." As I said, I am the system administrator.

Welcome
You are only the owner of the computer, this is the real boss. See if he/she will solve your problem
http://www.vistax64.com/tutorials/67567-administrator-account.html
http://windows.microsoft.com/en-US/windows-vista/Set-up-Parental-Controls

I tried disabling the built in administrator and there's no change. I'm still unable to access the parental controls for the standard accounts.

Just so there is no miscommunication, you enabled the adminstrator, correct?
http://www.vistax64.com/tutorials/95139-parental-controls-setup-use.html