BRepAlgoAPI_Fuse error?

Hello all,

running on version 7.7.0

if I "fuse" two or multiple TopoDS_Shape (made with BRepPrimAPI_MakePrism, BRepPrimAPI_MakeCylinder, BRepPrimAPI_MakeBox etc) with BRepAlgoAPI_Fuse all works as expect. See picture 1.png

if I "fuse" a BRepPrimAPI_MakeCylinder with a "self made" cube (picture 2.png) then I get a strange result: the "fuse" only works from the point both shapes are in common. hard to explain so please see the picture 3.png.

I am stuck since 2 days - any help is much appreciated. Thanks!! 

code for the working cube:

    // Dimensions of the cube
    double length = 500.0; // Length along X-axis
    double width = 100.0;  // Width along Y-axis
    double height = 1000.0; // Height along Z-axis

    // Create the cube as a TopoDS_Shape
    TopoDS_Shape cube = BRepPrimAPI_MakeBox(length, width, height).Shape();

code for my custom shape what doesn't work correct:

    double height = 1000;

    // Define the 8 points
    // bottom
    gp_Pnt p1(0, 0, 0);  // Point 1
    gp_Pnt p2(500, 0, 0);  // Point 2
    gp_Pnt p3(500, 100, 0);  // Point 3
    gp_Pnt p4(0, 100, 0);  // Point 4

    // top
    gp_Pnt p5(0, 0, height);  // Point 5
    gp_Pnt p6(100, 0, height);  // Point 6
    gp_Pnt p7(100, 100, height);  // Point 7
    gp_Pnt p8(0, 100, height);  // Point 8

    // Create vertices
    TopoDS_Vertex v1 = BRepBuilderAPI_MakeVertex(p1);
    TopoDS_Vertex v2 = BRepBuilderAPI_MakeVertex(p2);
    TopoDS_Vertex v3 = BRepBuilderAPI_MakeVertex(p3);
    TopoDS_Vertex v4 = BRepBuilderAPI_MakeVertex(p4);
    TopoDS_Vertex v5 = BRepBuilderAPI_MakeVertex(p5);
    TopoDS_Vertex v6 = BRepBuilderAPI_MakeVertex(p6);
    TopoDS_Vertex v7 = BRepBuilderAPI_MakeVertex(p7);
    TopoDS_Vertex v8 = BRepBuilderAPI_MakeVertex(p8);

    // Create edges by connecting the vertices
    TopoDS_Edge e1 = BRepBuilderAPI_MakeEdge(v1, v2);
    TopoDS_Edge e2 = BRepBuilderAPI_MakeEdge(v2, v3);
    TopoDS_Edge e3 = BRepBuilderAPI_MakeEdge(v3, v4);
    TopoDS_Edge e4 = BRepBuilderAPI_MakeEdge(v4, v1);

    TopoDS_Edge e5 = BRepBuilderAPI_MakeEdge(v5, v6);
    TopoDS_Edge e6 = BRepBuilderAPI_MakeEdge(v6, v7);
    TopoDS_Edge e7 = BRepBuilderAPI_MakeEdge(v7, v8);
    TopoDS_Edge e8 = BRepBuilderAPI_MakeEdge(v8, v5);

    TopoDS_Edge e9 = BRepBuilderAPI_MakeEdge(v1, v5);
    TopoDS_Edge e10 = BRepBuilderAPI_MakeEdge(v2, v6);
    TopoDS_Edge e11 = BRepBuilderAPI_MakeEdge(v3, v7);
    TopoDS_Edge e12 = BRepBuilderAPI_MakeEdge(v4, v8);

    // Create wires for each face (4 edges per face)
    TopoDS_Wire w1 = BRepBuilderAPI_MakeWire(e1, e2, e3, e4); // Bottom face
    TopoDS_Wire w2 = BRepBuilderAPI_MakeWire(e5, e6, e7, e8); // Top face
    TopoDS_Wire w3 = BRepBuilderAPI_MakeWire(e1, e9, e5, e10); // Side face
    TopoDS_Wire w4 = BRepBuilderAPI_MakeWire(e2, e10, e6, e11); // Side face
    TopoDS_Wire w5 = BRepBuilderAPI_MakeWire(e3, e11, e7, e12); // Side face
    TopoDS_Wire w6 = BRepBuilderAPI_MakeWire(e4, e12, e8, e9); // Side face

    // Create faces
    TopoDS_Face f1 = BRepBuilderAPI_MakeFace(w1); // Bottom face
    TopoDS_Face f2 = BRepBuilderAPI_MakeFace(w2); // Top face
    TopoDS_Face f3 = BRepBuilderAPI_MakeFace(w3); // Side face
    TopoDS_Face f4 = BRepBuilderAPI_MakeFace(w4); // Side face
    TopoDS_Face f5 = BRepBuilderAPI_MakeFace(w5); // Side face
    TopoDS_Face f6 = BRepBuilderAPI_MakeFace(w6); // Side face


    // Combine faces into a compound shape
    TopoDS_Shell shell;
    BRep_Builder builder;
    builder.MakeShell(shell);
    builder.Add(shell, f1);
    builder.Add(shell, f2);
    builder.Add(shell, f3);
    builder.Add(shell, f4);
    builder.Add(shell, f5);
    builder.Add(shell, f6);

    BRepBuilderAPI_MakeSolid solidMaker(shell);

both shape are transformed in plus X and minus Z:

    gp_Trsf aTrsf;
    aTrsf.SetTranslationPart(gp_Vec(500.0, 0.0, -500.0));
    gp_Quaternion q;
    q.SetEulerAngles(gp_Extrinsic_XYZ, 0, 0, 0.1);
    aTrsf.SetRotationPart(q);


for the cube:
    return BRepBuilderAPI_Transform(cube, aTrsf).Shape();


for the self made:
    return BRepBuilderAPI_Transform(solidMaker.Shape(), aTrsf).Shape();

then finally the fusion between a cylinder and the cube or custom shape:

aCylinder = BRepPrimAPI_MakeCylinder(anAxis, diameter/2, width).Shape();

works as expected:
BRepAlgoAPI_Fuse(aCylinder , aCube)

does not work correct:
BRepAlgoAPI_Fuse(aCylinder , aCustomShape)