in asp.net 2.0, if you setup a masterpage and declare a public property in it to be consumed by the content page, you must use the mastertype directive in the aspx content page or your codebehind will complain on compile about a statement like:
Master.PublicProperty = "value";
The mastertype directive to put in the aspx content page looks like this:
<%@ MasterType VirtualPath="~/FilenameOfTheMasterPage.master" %>