How to add opacity to objects in directX11 with shaders

I'm new to directx and I need to set up opacity in my shaders. I don't use textures or anything and I just need to add opacity to whole objects based on one variable in shader.

I've tried to simply put this variable in shader's output color alpha channel, but it didn't work and I guess that the solution of this problem is not in shaders. This is my shader so far.

cbuffer ConstantBuffer : register(b0)
{
    matrix World;
    matrix View;
    matrix Projection;
    float4 vLigthDir[2];
    float4 vLigthColor[2];
    float4 vOutputColor;
    float intensity;
    float3 colors;
}

struct VS_INPUT
{
    float4 pos : POSITION;
    float3 norm : NORMAL;
};

struct PS_INPUT
{
    float4 pos : SV_POSITION;
    float3 norm : TEXCOORD0;
};

PS_INPUT VS(VS_INPUT input)
{
    PS_INPUT output = (PS_INPUT) 0;
    output.pos = mul(input.pos, World);
    output.pos = mul(output.pos, View);
    output.pos = mul(output.pos, Projection);
    output.norm = mul(input.norm, World);

    return output;
}

float4 PS(PS_INPUT input) : SV_Target
{
    float4 finalColor = 0;
    finalColor.r = colors.r;
    finalColor.g = colors.g;
    finalColor.b = colors.b;
    finalColor.a = intensity;
    return finalColor;
}

float4 PSSolid(PS_INPUT input) : SV_Target
{
    return vOutputColor;
}

//Create BlendState
    D3D11_BLEND_DESC blendDesc;
    blendDesc.AlphaToCoverageEnable = false;
    blendDesc.IndependentBlendEnable = false;

    blendDesc.RenderTarget[0].BlendEnable = true;
    blendDesc.RenderTarget[0].SrcBlend = D3D11_BLEND_SRC_ALPHA;
    blendDesc.RenderTarget[0].DestBlend = D3D11_BLEND_INV_SRC_ALPHA;
    blendDesc.RenderTarget[0].BlendOp = D3D11_BLEND_OP_ADD;
    blendDesc.RenderTarget[0].SrcBlendAlpha = D3D11_BLEND_ONE;
    blendDesc.RenderTarget[0].DestBlendAlpha = D3D11_BLEND_ZERO;
    blendDesc.RenderTarget[0].BlendOpAlpha = D3D11_BLEND_OP_ADD;
    blendDesc.RenderTarget[0].RenderTargetWriteMask = D3D11_COLOR_WRITE_ENABLE_ALL;

    hr = g_pd3dDevice->CreateBlendState(&blendDesc, &pBlendState);

//Using BlendState
    float blendFactor[4] = { 1.0f, 1.0f, 1.0f, 1.0f };
    UINT sampleMask = 0xffffffff;
    g_pImmediateContext->OMGetBlendState(&pBlendState, blendFactor, &sampleMask);
///////////Rendering geometry part///////////
    g_pImmediateContext->OMGetBlendState(NULL, NULL, NULL);

I expect some objects to have opacity, but instead nothing happenening at all, there are just solid color.