I installed Nokia S60 2nd FP2 (for visual Studio 6, chinese), successfully built example applications...and it's my default SDK because I have no other SDKs
But when I tried to install SIP plug-in 4 (Nokia_SIP_ Plug-in_4.0_for_Series_60 .zip), I saw a dialog which said
"Series 60 SDK 2.6 is required but is not installed into your system or is not default SDK. Please install SDK or choose it as default before installing SIP Plug-in"
Then the installer quit.
What should I do? What's S60 SDK 2.6?