How to lighting object by self shader?

Hi,
There is a devil(left) by shader "Diffuse" (the unity default shader), and a swordman(right) by shader "MyShader"(the shader that I wrote).
I use pix of directx to find how to render lighting:

1. draw devil (no lighting)
2. draw swordman (no lighting)
3. draw devil (lighting, alpha is add (one one)
4. there is not draw swordman(lighting)

Why the swordman isn't draw lighting like devil? Thanks.

Code (CSharp):

1. Shader "MyShader" {
2.     Properties {
3.         _MainTex ("Base (RGB)", 2D) = "white" {}
4.     }
5.     SubShader {
6.         Tags { "RenderType"="Opaque" }
7.         LOD 200
8.         Pass
9.         {
10.             Tags {"LightMode" = "ForwardBase"}
11.             Cull back
12.             Lighting off
13.             Blend off          
14.             CGPROGRAM
15.             #pragma multi_compile_fwdbase
16.             #pragma vertex Vert_T
17.             #pragma fragment Frag_T
18.             #pragma fragmentoption ARB_precision_hint_fastest
19.                      
20.             PX_T_outvs Vert_T(PX_T_invs i)
21.            {
22.             PX_T_outvs o;
23.             o.pos = mul (UNITY_MATRIX_MVP, i.vertex);  
24.             o.texcoord = i.texcoord;
25.             return o;
26.            }
27.            fixed4 Frag_T( PX_T_outvs i ) : COLOR
28.            {
29.               fixed4 colorTex = tex2D(_MainTex, i.texcoord);
30.               return colorTex;
31.             }
32.            ENDCG
33.           }
34.       }
35.       FallBack "Diffuse"
36.     }