nodejs cannot access an exported method Object #<Object> has no method

i exported some of my variable an a function in nodejs like below:

app.js:

var setting;
var savesetting = function(val, callback){ .....}
module.export =setting;
module.export = savesetting;

index.js:

var appjs = require('app');
appjs.savesettings(0,1);

appjs.savesettings(); cause an error which is:

Express
500 TypeError: Object #<Object> has no method 'savesettings'

any idea?

var app = {
   setting:{},
   savesetting : function(val, callback){ .....}
}
module.exports = app;

http://nodejs.org/api/modules.html