just upgrade to iPhone SDK 4 - Base sdk missing ...

Just download & installed the iPhone SDK 4 with XCode 3.2.3

While I have a little problem that the old project have "Base SDK missing" issues.
I solved the problem this morning.

To solve it, right on the project, and click "Get Info",
in the "Get Info" panel, there is a opiton call "Base SDK" (under the Build tag)
you have to select a available "SDK varion" in order to compile & run.

So, you can select SDK 3.2 or greater , in my case, everything go fine.

I also try to cmpile my working Cocos2d project, and it works.

:)