Why is my normal vector always blank? HLSL - vector

Question

I am trying to create a basic diffuse shader with HLSL, with this rbwhitaker tutorial. The shader runs without errors and can display triangles, but it seems that the Normal input to the vertex shader is never given a value, which causes the diffuse lighting to break. I tested this by setting the output color to white, and then subtracting the normal, but there was never any variation in colors, it stayed white. My shader code is below.
float4x4 World;
float4x4 View;
float4x4 Projection;
float4x4 WorldInverseTranspose;
float3 DiffuseLightDirection = float3(1, 0, 0);
float4 DiffuseColor = float4(1, 1, 1, 1);
float DiffuseIntensity = 1.0;
float4 AmbientColor = float4(1, 1, 1, 1);
float AmbientIntensity = 0.1;
struct VertexShaderInput
{
float4 Position : POSITION0;
float4 Normal : NORMAL0;
};
struct VertexShaderOutput
{
float4 Position : POSITION0;
float4 Color : COLOR0;
};
VertexShaderOutput VertexShaderFunction(VertexShaderInput input)
{
VertexShaderOutput output;
float4 worldPosition = mul(input.Position, World);
float4 viewPosition = mul(worldPosition, View);
output.Position = mul(viewPosition, Projection);
float4 normal = mul(input.Normal, WorldInverseTranspose);
float lightIntensity = dot(normal, DiffuseLightDirection);
output.Color = saturate(DiffuseColor * DiffuseIntensity * lightIntensity);;
return output;
}
float4 PixelShaderFunction(VertexShaderOutput input) : COLOR0
{
return saturate(input.Color + AmbientColor * AmbientIntensity);
}
technique Diffuse
{
pass Pass1
{
VertexShader = compile vs_2_0 VertexShaderFunction();
PixelShader = compile ps_2_0 PixelShaderFunction();
}
}
EDIT:
I think it is probably because I don't directly pass the normal to the shader, but I don't know how to compute it if there isn't a built in way.