.dae/.stl meshes repels each other, when standart box do not.

edit

I want to robot laid tower of cubes. When I use simple models of cubes, they lie on each other.

<box> 1 1 1</box>

But if I use cubes of .dae or .stl they begin to repel each other and the tower collapses.

<sdf version ='1.5'>
<model name='name'>
<link name ='link'>
    <inertial>
        <mass>1.0</mass>
    </inertial>
    <collision name ='collision'>
        <geometry>
            <mesh> <uri> file://media/models/cube.stl </uri></mesh> 
        </geometry>
    </collision>
    <visual name ='visual'>
        <geometry>
            <mesh> <uri> file://media/models/cube.dae </uri></mesh> 
        </geometry>
        <material>
            <script>
                <uri>file://media/materials/scripts/gazebo.material</uri>
                <name>Gazebo/SkyBlue</name>
            </script>
        </material>
    </visual>
</link>
</model>
</sdf>

I've tried to add [inertia] and [collision] -> [surface] properties, but it doesn't help. What am I missing?