3D text visible through plane/Cube

Hey guys … I am using 3D text for displaying text.But when i create another plane/Cube over it but it is visible through them.I changed the material of the plane/Cube with the colour but still its the same.How to make them invisible when another game object comes over it.

The default 3d text shader displays text in front of all other objects, just like GuiText. You should create a new material for your text using a shader such as http://wiki.unity3d.com/index.php?title=3DText