VTK: can't color the mapper after using warpScalar

Question

I have been trying to apply a warpScalar filter to my dataset file and have it in color. I have done this in paraview(1st picture) but somehow I'm not able to do this in VTK code. I manage to apply color to a mapper or the warpScalar by itself. But can't merge them and have a warpped and colored plane.

Code:

int main(int, char *[])
{   
    vtkRenderer *ren = vtkRenderer::New();
    ren->SetBackground(0.3, 0.2, 0.4);
    vtkRenderWindow *renWin = vtkRenderWindow::New();
    renWin->AddRenderer(ren);
    renWin->SetSize(900, 900);
    vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
    iren->SetRenderWindow(renWin);
    vtkInteractorStyleTrackballCamera *style = vtkInteractorStyleTrackballCamera::New();
    iren->SetInteractorStyle(style);        

    vtkDataSetReader*read = vtkDataSetReader::New();
    read->SetFileName("ubgrid.vtk");
    read->ReadAllScalarsOn();
    read->Update();
    
    //WRAP
    vtkNew<vtkWarpScalar> warp;
    warp->SetInputConnection(read->GetOutputPort());
    warp->SetInputArrayToProcess(vtkDataSetAttributes::SCALARS, 0, 0, vtkDataObject::FIELD_ASSOCIATION_POINTS, "group/Scalar2"); //Warp by using group/scalar2
    warp->SetScaleFactor(1.0);
    warp->UseNormalOn();
    warp->Update();

    //MERGE
    vtkMergeFilter*merge = vtkMergeFilter::New();
    merge->SetGeometryInputData(warp->GetOutput());
    merge->SetScalarsData(read->GetOutput());

    //MAPPER
    vtkDataSetMapper*mapper = vtkDataSetMapper::New();
    mapper->SetInputConnection(merge->GetOutputPort());
    mapper->SetColorModeToMapScalars();
    mapper->ScalarVisibilityOn();
    mapper->SetScalarModeToUseFieldData();
    mapper->SelectColorArray("group/Scalar1");
    mapper->ColorByArrayComponent("group/Scalar1", 0); //But color it in group/scalar1
    //mapper->ImmediateModeRenderingOff();
    
    //ACTOR
    vtkActor*actor = vtkActor::New();
    actor->SetMapper(mapper);

    ren->ResetCamera();
    ren->AddActor(actor);
    renWin->Render();
    iren->Start();

    // Clean up
    ren->Delete();
    renWin->Delete();
    iren->Delete();
    mapper->Delete();
    actor->Delete();
    return(0);
}

Paraview output:

Only warpScalar output:

Color output without warpScalar: