node.js express.js object is not a function call_non_function

I have this error:

TypeError: object is not a function
at Object.CALL_NON_FUNCTION (native)

For this line:

var app=express();

I tryed to install express/connect again, but.. nothing.

Thanks!

EDIT

I'm express 2.5.8.

my code:

error:

    var http=require('http');
    var app=express();
    var server=http.createServer(app);

(i forget why i need to use this code, i think for cookie handshake works. I have resole the probleme (hanskake cookie) editing manager.js, so i dont need to use this code. But can be interesting to understand why no works (and why i wanted to use)).

no error: var app=express.createServer();