Difficulties changing permissions for a folder in Windows 7

I am trying to delete a folder in Windows 7 and I get the following error:

"You need permission to perform this action"

When I go into "Properties" and then the "Security" tab, my useame does not show up on the list of "Group or user names". However, if I go into the Advanced Settings and click on "Owner", it says that my useame is the current owner. But once again, my useame does not show up in the "Permissions" tab.

I am an Administrator. Any help is appreciated.

Cheers