There is a bug in Visual Studio 2008 Beta 2 that says you haven´t declared writeAccessProperties when you activate profileService in web.config. It´s easy to fix, though.
What you have to do is change line 4121 in
%Program Files%\Microsoft Visual Studio 9.0\Xml\Schemas\DotNetConfig.XSD.
Old:
<xs:attribute name="writeAccessProperites" type="xs:string" use="optional" />
New:
<xs:attribute name="writeAccessProperties" type="xs:string" use="optional" />