Models doesn't appear when setting up gazebo programmatically

Hi everyone, I tried the example animated_box which setup the server with a box inside.Then I launch the gzclient, it connect to the server and the box appears in the "models" but not on the render. I also tried to setup other models programmatically but they don't move (it's like they're not being simulated): they don't fall down for example (gravity flag is true in the model). Is there a way to make this work? I'm working on Windows with gazebo 7 compiled in 32bits with Visual Studio 2013. Also unlike the tutorial I use the latest version of OGRE. Thank you! XB32Z