Problem with shadow casting when assign my shader

Hi, When i assign my shader to a GameObject, it doesn’t receive and doesn’t cast shadows while before assigning shader,the GameObject worked properly with shadows.
For example a shader like this:

Shader "Examples/2 Alpha Blended Textures" {
    Properties {
        _MainTex ("Base (RGB)", 2D) = "white" {}
        _BlendTex ("Alpha Blended (RGBA) ", 2D) = "white" {}
    }
    SubShader {
        Pass {
            // Apply base texture
            SetTexture [_MainTex] {
                combine texture
            }
            // Blend in the alpha texture using the lerp operator
            SetTexture [_BlendTex] {
                combine texture lerp (texture) previous
            }
        }
    }
}

How do I correct it? Thanks

That shader is written in pure ShaderLab; it is known as a “fixed function” shader. You can’t do shadows with that. Learn about surface shaders.