Custom shader - failed to create texture

#include "ReShade.fxh"

// --- Texture and Sampler Block (unique names) ---

texture DDDPaletteTex < source = "DDDpalette.png"; >;

sampler DDDPaletteSampler
{
    Texture = DDDPaletteTex;
    MinFilter = POINT;
    MagFilter = POINT;
    MipFilter = NONE;
    AddressU = Clamp;
    AddressV = Clamp;
};

// --- User Controls ---

uniform float fUIBlend <
    ui_type = "drag";
    ui_label = "Blend";
    ui_min = 0.0; ui_max = 1.0;
    ui_step = 0.01;
> = 1.0;

// Set this to your palette width/height (default 256)
uniform float fUIDDDPaletteSize <
    ui_type = "slider";
    ui_label = "Palette Size (pixels)";
    ui_min = 16; ui_max = 1024;
    ui_step = 1;
> = 256.0;

// --- Palette Mapping Function ---

float3 MapColorThroughDDDPalette(float3 color)
{
    // Use R and G channels for X/Y lookup into palette
    float2 uv = float2(color.r, color.g);
    // Sample center of each texel (avoids seams)
    uv = (uv * (fUIDDDPaletteSize - 1.0) + 0.5) / fUIDDDPaletteSize;
    return tex2D(DDDPaletteSampler, uv).rgb;
}

// --- Main Shader ---

float3 DDDpalette_PS(float4 vpos : SV_Position, float2 texcoord : TexCoord) : SV_Target
{
    float3 original = tex2D(ReShade::BackBuffer, texcoord).rgb;
    float3 mapped = MapColorThroughDDDPalette(original);

    return lerp(original, mapped, fUIBlend);
}

// --- Technique ---

technique DDDpalette
{
    pass
    {
        VertexShader = PostProcessVS;
        PixelShader = DDDpalette_PS;
    }
}