Render Texture is black

Good afternoon.
I’m trying to get a Render Texture by GetTemporaryRT.
However, a black texture is returning to me.

The console shows:

CommandBuffer: temporary render texture _CameraFrameBuffer not found while executing PostProcessing (SetGlobalTexture)
UnityEngine.Rendering.ScriptableRenderContext:Submit()
CameraRenderer:Submit() (at Assets/MagicByte/Runtime/CameraRenderer.cs:116)
CameraRenderer:Render(ScriptableRenderContext, Camera, Boolean, Boolean, ShadowSettings, PostProcessingAsset) (at Assets/MagicByte/Runtime/CameraRenderer.cs:78)
MagicByteRenderPipeline:Render(ScriptableRenderContext, Camera[]) (at Assets/MagicByte/Runtime/MagicByteRenderPipeline.cs:23)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

Codes:

CameraClearFlags flags = camera.clearFlags;

        PostProcessingCamera PPC = camera.GetComponent<PostProcessingCamera>();
        if (PPC)
        {

            postStack.Setup(context, camera, ppAsset);

            if (flags > CameraClearFlags.Color)
            {
                flags = CameraClearFlags.Color;
            }

            buffer.GetTemporaryRT(frameBufferId, camera.pixelWidth, camera.pixelHeight, 32, FilterMode.Bilinear, RenderTextureFormat.Default);
            buffer.SetRenderTarget(frameBufferId, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store);

            PPC.OnRenderCamera();
            postStack.PostProcessingDrawing(frameBufferId, BuiltinRenderTextureType.CameraTarget, PPC.OnRenderTone(), 0, buffer);

        }

        DrawGizmos();
        Cleanup();
        Submit();
    }
void Cleanup()
    {
        lighting.Cleanup();
        buffer.ReleaseTemporaryRT(frameBufferId);
    }

PostFXStack Script:

using UnityEngine;
using UnityEngine.Rendering;

public partial class PostProcessingStack
{

    const string bufferName = "PostProcessing";
    int fxSourceId = Shader.PropertyToID("_PostFXSource");
    CommandBuffer buffer = new CommandBuffer
    {
        name = bufferName
    };

    ScriptableRenderContext context;

    Camera camera;

    PostProcessingAsset settings;
    public bool IsActive = true;

    public void Setup(
        ScriptableRenderContext context, Camera camera, PostProcessingAsset settings
    )
    {
        this.context = context;
        this.camera = camera;
        this.settings = camera.cameraType <= CameraType.SceneView ? settings : null;

    }

    public void PostProcessingDrawing(int sourceId, RenderTargetIdentifier to, Material material, int pass, CommandBuffer cmd)
    {
        Drawing(sourceId, to, material, pass, cmd);
        context.ExecuteCommandBuffer(buffer);
        buffer.Clear();
    }

    void Drawing(RenderTargetIdentifier from, RenderTargetIdentifier to, Material material, int pass,CommandBuffer cmd)
    {
        cmd.SetGlobalTexture(fxSourceId, from);
        buffer.SetRenderTarget(to, RenderBufferLoadAction.DontCare, RenderBufferStoreAction.Store);
        if(settings != null)
        buffer.DrawProcedural(Matrix4x4.identity, material, pass,MeshTopology.Triangles, 3);
    }
}

6163851--674181--sdfg.PNG

Shader (Vertex and Pixel):

Shader "Hidden/TonemappingShader"
{
    Properties
    {
        //_MainTexCamera ("Texture", 2D) = "white" {}
    }
    SubShader
    {
        Tags { "RenderType"="Opaque" }

        ZTest Always Cull Off ZWrite Off

        HLSLINCLUDE
        #include "../ShaderLibrary/Common.hlsl"
        ENDHLSL

        Pass
        {
            HLSLPROGRAM
            #pragma target 3.5
            #pragma vertex DefaultPassVertex
            #pragma fragment frag

            #include "../ShaderLibrary/UnityInput.hlsl"

            TEXTURE2D(_PostFXSource);
            SAMPLER(sampler_PostFXSource);

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct Varyings {
                float4 positionCS : SV_POSITION;
                float2 fxUV : VAR_FX_UV;
            };

            Varyings DefaultPassVertex(uint vertexID : SV_VertexID) {
                Varyings output;
                output.positionCS = float4(
                    vertexID <= 1 ? -1.0 : 3.0,
                    vertexID == 1 ? 3.0 : -1.0,
                    0.0, 1.0
                    );
                output.fxUV = float2(
                    vertexID <= 1 ? 0.0 : 2.0,
                    vertexID == 1 ? 2.0 : 0.0
                    );
                if (_ProjectionParams.x < 0.0) {
                    output.fxUV.y = 1.0 - output.fxUV.y;
                }
                return output;
            }

float4 GetSource(float2 fxUV) {
    return SAMPLE_TEXTURE2D(_PostFXSource, sampler_PostFXSource, fxUV);
}
float4 frag (Varyings i) : SV_Target
{

                float4 color = GetSource(i.fxUV);

                float3 hsv = RGBtoHSV(color.rgb);
                hsv.x = gmod(hsv.x + _HSV.x, 1.0);
                hsv.yz *= _HSV.yz;
                color.rgb = saturate(HSVtoRGB(hsv));

                        if (_Tone == 1) color.rgb = linearT(color.rgb);
                        if (_Tone == 2) color.rgb = simpleReinhard(color.rgb);
                        if (_Tone == 3) color.rgb = lumaBasedReinhard(color.rgb);
                        if (_Tone == 4) color.rgb = Photographic(color.rgb);
                        if (_Tone == 5) color.rgb = whitePreservingLuma(color.rgb);       
                        if (_Tone == 6) color.rgb = filmic(color.rgb);
                        if (_Tone == 7) color.rgb = ACESFilm(color.rgb);
                        if (_Tone == 8) color.rgb = Gray(color.rgb);

                color.rgb = pow(color.rgb,_Gamma);

                half3 lms = mul(LIN_2_LMS_MAT, color.rgb);
                lms *= _WhiteBalance;
                color.rgb = mul(LMS_2_LIN_MAT, lms);

                color.rgb = saturate((color.rgb - 0.5) * _Contrast + 0.5);

                return color;
            }
            ENDHLSL
        }
    }
}

I fixed the problem by changing GetTemporaryRT to preRender the camera.