Strange issue with stencil buffer and draw order

Im drawing two quads, A which is opac black and B which is transparent black. They are using the same shader with a stencilbuffer and an alpha-parameter. I want B to not draw over A, which it is as you can see in the example image. I use the stencilbuffer to avoid drawing internally overlapping triangles. My real case is more complex than this example image but this is basically the problem I get. It doesnt matter what order Im drawing the quads in or which z-order they are in. B is always drawing over A. This seem almost impossible to me but apparently not. Anybody understand whats wrong here?

 Shader "My/GuideLine" {
       
     Properties {
         _Opacity ("Opacity", Range (0.0, 1.0)) = 1.0
         _MainTex ("Texture", 2D) = "white" {}
     }
   
     SubShader {
        Tags { "Queue" = "Transparent" }
         Pass {
       
             Stencil {
                 Ref 10
                 ReadMask 10
                 Comp NotEqual
                 Pass Replace
             }
           
             Blend SrcAlpha OneMinusSrcAlpha
             Lighting Off
             ZWrite Off
             Cull Off
 
             SetTexture [_MainTex]
             {
                 constantColor (1, 1, 1, [_Opacity])
                 combine texture * constant
             }
         }
     }
 }

 Graphics.DrawMesh(A.Mesh, _matrix, A.Material, 0, gameObject.camera, 0);
 Graphics.DrawMesh(B.Mesh, _matrix, B.Material, 0, gameObject.camera, 0);

UPDATE: The problem has been solved but for the record I didn't delete this post. It could be helpful for others.

The solution: It doesnt matter in what order the DrawMesh is called BUT in what order I have created my mesh-geometries! This was news to me.