Problem displaying decals

I am trying to mark target points in a tile-based puzzle game. The tiles are beveled cubes exported from Blender with diffuse + normal textures applied.

I have copied some code from the Decals sample (Raycast() and PaintDecal() functions), but when I click on the tiles I am getting inconsistent results:

The crosshair is a 128x128 image with white circles on black background. I created the material from the material editor:

<?xml version="1.0"?> <material> <technique name="Techniques/DiffAdd.xml" quality="0" loddistance="0" /> <texture unit="diffuse" name="Textures/crosshair2.png" /> <parameter name="UOffset" value="1 0 0 0" /> <parameter name="VOffset" value="0 1 0 0" /> <parameter name="MatDiffColor" value="1 1 0 0.5" /> <parameter name="MatEmissiveColor" value="0 0 0" /> <parameter name="MatEnvMapColor" value="1 1 1" /> <parameter name="MatSpecColor" value="0 0 0 1" /> <parameter name="Roughness" value="0.5" /> <parameter name="Metallic" value="0" /> <cull value="ccw" /> <shadowcull value="ccw" /> <fill value="solid" /> <depthbias constant="0" slopescaled="0" /> <renderorder value="128" /> </material>


    void App::HandleLeftMouseDown(StringHash eventType, VariantMap& eventData)
        Vector3 hitPosition;
        Drawable* hitDrawable;

        if (Raycast(64.0f, hitPosition, hitDrawable))
            Node* targetNode{ hitDrawable->GetNode() };
            DecalSet* decals{ targetNode->GetComponent<DecalSet>() };
            if (decals)
            ResourceCache* cache{ GetSubsystem<ResourceCache>() };
            decals = targetNode->CreateComponent<DecalSet>();
            Vector3 position{ targetNode->GetPosition() };
            position.y_ = hitPosition.y_;
            Quaternion rotation{ 90, 0, 0 };
            decals->AddDecal(hitDrawable, position, rotation, 0.5f, 1.0f, 1.0f,
                Vector2::ZERO, Vector2::ONE);

** EDIT:
I just tried changing the size parameter in AddDecal from 0.5f to 1.0f and it kinda works:

<depthbias constant="0.0" slopescaled="-2.000" />

in material

Thanks Ivan, I finally solved with this:

This is the same as the Decals sample, but it didn’t work before. I probably changed something else along the way(?)