invalid input semantic 'POSITION': Legal indices are in [1,15]解决方案

invalid input semantic 'POSITION': Legal indices are in [1,15]
error X4502: invalid input semantic 'POSITION': Legal indices are in [1,15]
error X4502: invalid ps_3_0 input semantic 'POSITION'

float4x4 WorldMatrix;
float4x4 ViewProjMatrix;

float3 lightpos;
float4 lightcolor = float4(1.0,0.0,0.0,1.0);
float3 lightdir;
float lightcosInnerCone = 3.14/4.0;
float lightcosOuterCone = 3.14/3.0;

texture texture0;

sampler Sampler0= sampler_state
{
texture = <texture0>;
Filter = MIN_MAG_MIP_LINEAR;
AddressU = Wrap;
AddressV = Wrap;
};

//
float spotlight_parameter(float3 pos,
  float3 lightposition,
  float3 lightdiretion)
{
float3 V = normalize(pos - lightposition);  
float cosDirection= dot(V,lightdiretion);
return smoothstep(lightcosOuterCone,lightcosInnerCone,cosDirection);
}

struct VS_INPUT
{
  float3 Position :POSITION;
  float3 Normal :NORMAL;
  float2 TexCoord :TEXCOORD0;
};


struct VS_OUTPUT
{
float4 position :POSITION;
float2 texcoord :TEXCOORD0;
};


VS_OUTPUT mainVS0(VS_INPUT IN)
{
VS_OUTPUT OUT;
float4 finalpos = mul(WorldMatrix,float4(IN.Position,1.0));
finalpos = mul(ViewProjMatrix,finalpos);
//vertex pos
OUT.position = finalpos;

//light pos 
finalpos = mul(WorldMatrix,float4(lightpos,1.0));
finalpos = mul(ViewProjMatrix,finalpos);
lightpos = finalpos.xyz;

//light direction
finalpos = mul(WorldMatrix,float4(lightdir,1.0));
finalpos = mul(ViewProjMatrix,finalpos);
lightdir = finalpos.xyz;

OUT.texcoord = IN.TexCoord;
return OUT;
}

float4 mainPS0(VS_OUTPUT IN):COLOR
{
float4 texColor = tex2D(Sampler0,IN.texcoord);
float spotEffect = spotlight_parameter(IN.position.xyz,lightpos,lightdir);
float4 finalcolor;
finalcolor = lerp(texColor,lightcolor,spotEffect);
return finalcolor;
}

technique technique0
{
  pass P0
  {
  CullMode = CCW;
  VertexShader = compile vs_3_0 mainVS0();
  PixelShader = compile ps_3_0 mainPS0();
  }
}

大侠帮忙解决，谢谢

[解决办法]
ps的输入参数不支持POSITION,改用

C/C++ code

struct PS_INPUT{ float2 texcoord :TEXCOORD0; };
[解决办法]
VS_OUTPUT里面必须含有POSITION

float4x4 WorldMatrix;  
float4x4 ViewProjMatrix;  

float3 lightpos;  
float4 lightcolor = float4(1.0,0.0,0.0,1.0);  
float3 lightdir;  
float lightcosInnerCone = 3.14/4.0;  
float lightcosOuterCone = 3.14/3.0;  

texture texture0;  

sampler Sampler0= sampler_state  
{  
texture = <texture0>;  
Filter = MIN_MAG_MIP_LINEAR;  
AddressU = Wrap;  
AddressV = Wrap;  
};  

//  
float spotlight_parameter(float3 pos,  
                         float3 lightposition,  
                         float3 lightdiretion)  
{  
float3 V = normalize(pos - lightposition); 
float cosDirection= dot(V,lightdiretion);  
return smoothstep(lightcosOuterCone,lightcosInnerCone,cosDirection);  
}  

struct VS_INPUT  
{  
   float3 Position  :POSITION;  
   float3 Normal    :NORMAL;  
   float2 TexCoord  :TEXCOORD0;  
};  


struct VS_OUTPUT  
{  
float4 position :POSITION;   
 
float2 texcoord :TEXCOORD0;  
float4 pos:TEXCOORD1; 
};  

struct PS_INPUT
{ 
float2 texcoord :TEXCOORD0; 
float4 pos:TEXCOORD1; 
}; 

VS_OUTPUT mainVS0(VS_INPUT IN)  
{  
VS_OUTPUT OUT;  
float4 finalpos = mul(WorldMatrix,float4(IN.Position,1.0));  
finalpos = mul(ViewProjMatrix,finalpos);  
//vertex pos  
OUT.position = finalpos;  
OUT.pos = finalpos;

//light pos  
finalpos = mul(WorldMatrix,float4(lightpos,1.0));  
finalpos = mul(ViewProjMatrix,finalpos);  
lightpos = finalpos.xyz;  

//light direction  
finalpos = mul(WorldMatrix,float4(lightdir,1.0));  
finalpos = mul(ViewProjMatrix,finalpos);  
lightdir = finalpos.xyz;  

OUT.texcoord = IN.TexCoord;  
return OUT;  
}  

float4 mainPS0(PS_INPUT IN):COLOR  
{  
float4 texColor = tex2D(Sampler0,IN.texcoord);  
float  spotEffect = spotlight_parameter(IN.pos.xyz,lightpos,lightdir);  
float4 finalcolor;  
finalcolor = lerp(texColor,lightcolor,spotEffect);  
return finalcolor;  
}  

technique  technique0  
{  
   pass P0  
   {  
     CullMode = CCW;  
     VertexShader = compile vs_3_0 mainVS0();  
     PixelShader  = compile ps_3_0 mainPS0();  
   }  
}