DirectX HLSL - Constant Buffer empty in Pixel Shader but not Vertex Shader - c++

Question

I am in the process of implementing lighting in my DirectX 11 project. The problem I have is that when I try to access a cbuffer value from the Pixel Shader function it's just returning float3(0, 0, 0) meanwhile when I access the same value in the Vertex Shader function it returns the correct value. Here is the shader:
/*********************************************\
VERTEX SHADER
\*********************************************/
//Constant buffers
cbuffer Object : register(cb0) {
float4x4 WorldMatrix;
};
cbuffer Camera : register(cb1) {
float4x4 ViewMatrix;
float4x4 ProjectionMatrix;
};
cbuffer LightBuffer : register(cb2) {
float3 AmbientColor;
}
//IO Structs
struct VS_INPUT {
float3 Position : POSITION;
float2 UV : TEXCOORD;
float3 Normal : NORMAL;
};
struct VS_OUTPUT {
float4 Position : SV_POSITION;
float2 UV : TEXCOORD;
float3 Normal : NORMAL;
};
VS_OUTPUT VS(VS_INPUT input){
VS_OUTPUT output;
float4 Position;
//Multiply position with AmbientColor (should be 1, 1, 1), position unchanged
Position = mul(ViewMatrix, float4(input.Position * AmbientColor, 1));
Position = mul(ProjectionMatrix, Position);
Position = mul(WorldMatrix, Position);
output.Position = Position;
output.UV = input.UV;
output.Normal = mul(WorldMatrix, input.Normal);
return output;
}
/*********************************************\
PIXEL SHADER
\*********************************************/
SamplerState TextureState;
Texture2D<float4> Texture;
float4 PS(VS_OUTPUT input) : SV_TARGET {
float4 MaterialColor = Texture.Sample(TextureState, input.UV);
//Multiply color with AmbientColor (should be 1, 1, 1), returns black
float3 FinalColor = MaterialColor.xyz * AmbientColor;
return float4(FinalColor, MaterialColor.a);
}
Here's is the value I'm sending (c++):
_LightsUniform.AmbientColor = XMFLOAT3(1, 1, 1);
DeviceContext->UpdateSubresource(_LightBuffer, 0, NULL, &_LightsUniform, 0, 0);
DeviceContext->VSSetConstantBuffers(2, 1, &_LightBuffer);
DeviceContext->PSSetConstantBuffers(2, 1, &_LightBuffer);
Here is the result:
http://i.gyazo.com/357f1ed3ea33e6569ad2346b368cd975.png
And result without multiplying color: http://gyazo.com/b60b385daa94d3373e9552a523928e3f
I can't see what is wrong. Anybody else had the same issue?

Answer 1

I found the problem. Turns out that the registers for my cbuffer(s) were wrong, I used cb# where b# should be used. (I misunderstood what was written here: https://msdn.microsoft.com/en-us/library/windows/desktop/hh447212(v=vs.85).aspx)
Wrong code:
cbuffer LightBuffer : register(cb2) {
Changed to:
cbuffer LightBuffer : register(b2) {