Depth buffer access from P3D post-processing system

Hi,

I'm making a simple post-processing shader for P3D v5, which requries depth input. However after drawing the depth buffer to the screen, I noticed that it's basically the grayscale version of the color buffer, instead of the expected depth buffer. Am I doing something wrong?

This is the shader code:

#include "Quad.sh"

Texture2D<float4> srcTex;
Texture2D<float> srcDepth;

float4 PsSSAOMain(PsQuad vert) : SV_Target
{
    uint2 texture_dimensions;
    srcDepth.GetDimensions(texture_dimensions.x, texture_dimensions.y);

    int3 texture_coordinates = int3(vert.texcoord * texture_dimensions, 0);
    float depth = srcDepth.Load(texture_coordinates);

    return float4(depth, depth, depth, 1.0);
}

This is the XML file for configuration:

<?xml version="1.0" encoding="UTF-8"?>

<SimBase.Document Type="AceXML" version="1,0">

    <PostProcessEffects.PostProcessDefinition>
        <EffectName>SSAO</EffectName>
        <ShaderFileName>SSAO.psh</ShaderFileName>
        <ShaderEntryPoint>PsSSAOMain</ShaderEntryPoint>
        <ColorRequest>TRUE</ColorRequest>
        <DepthRequest>TRUE</DepthRequest>
    </PostProcessEffects.PostProcessDefinition>

</SimBase.Document>

This is the result I'm getting:

It doesn't look like the depth buffer at all.

Thanks in advance.