Unable to reference SPUserToken or use SPSecurity classes

Hello,

http://i.imgur.com/9O9T4gI.png

Sorry for no link or image, there's an error trying to verify my account...

As shown in this image, I am unable to create a SPUserToken or run the SPSecurity.RunWithElevatedPrivileges() delegate in order to elevate the current user for the purpose of managing list item permissions. Is there a different Microsoft.Sharepoint library that I should be using?

Thanks for any help.

Ryan