Modelica: Class not found in scope

I am trying to create my own GreenEnergy library in OpenModelica. I reproduced a similar structure of the library to Modelica Standard Library, but unfortunately receiving the next error:

...
[GreenEnergy.Validation.Wall: 5:3-5:312]: Class GreenEnergy.HeatTransfer.Components.Wall not found in scope GreenEnergy.Validation.Wall.
...

I have next file(and its content) structure:

GreenEnergy

• package.mo

  within ;
  package GreenEnergy
  extends Modelica.Icons.Package;
  end GreenEnergy;
  

• HeatTransfer

  • package.mo

  within GreenEnergy;
  package HeatTransfer
  extends Modelica.Thermal.HeatTransfer;
  end HeatTransfer;
  

  • Components
    • package.mo

    within GreenEnergy.HeatTransfer;
    package Components
    extends Modelica.Thermal.HeatTransfer.Components;
    end Components;
    

    • Wall.mo

    within GreenEnergy.HeatTransfer.Components;
    
    model Wall
    
    import Modelica.Units.SI;
    import Modelica.Thermal.HeatTransfer;
    
    parameter SI.Area area = 1 "Wall area";
    parameter SI.Length thickness = 0.5 "Thickness of wall";
    parameter SI.Density density = 2000 "Wall density";
    parameter SI.ThermalConductivity thermal_conductivity = 0.62 
    "https://en.wikipedia.org/wiki/Thermal_conductivity";
    parameter SI.SpecificHeatCapacity specific_heat_capacity = 800 
    "Wall material specific heat capacity";
    parameter SI.Temperature initial_temperature = 288.15 "Initial 
    temperature of wall";
    
    final constant SI.HeatCapacity heat_capacity = area * thickness * 
    density * specific_heat_capacity;
    final constant SI.CoefficientOfHeatTransfer 
    coefficient_of_heat_transfer = thermal_conductivity * thickness;
    final constant SI.ThermalConductance thermal_conductance = area * 
    coefficient_of_heat_transfer;
    
    HeatTransfer.Components.HeatCapacitor heatCapacitor(C = 
    heat_capacity, T(displayUnit = "degC", fixed = true, start = 
    initial_temperature)) annotation(Placement(visible = true, 
    transformation(origin = {1, -33}, extent = {{-23, -23}, {23, 23}}, 
    rotation = 180)));
    HeatTransfer.Components.ThermalConductor thermalConductorOuter(G = 
    thermal_conductance / 2) annotation(Placement(visible = true, 
    transformation(origin = {-56, 0}, extent = {{-18, -18}, {18, 18}}, 
    rotation = 0)));
    HeatTransfer.Components.ThermalConductor thermalConductorInner(G = 
    thermal_conductance / 2) annotation(Placement(visible = true, 
    transformation(origin = {56, 0}, extent = {{-18, -18}, {18, 18}}, 
    rotation = 0)));
    HeatTransfer.Interfaces.HeatPort_a port_a 
    annotation(Placement(visible = true, transformation(origin = 
    {-100, 0}, extent = {{-10, -10}, {10, 10}}, rotation = 0), 
    iconTransformation(origin = {-66, 0}, extent = {{-10, -10}, {10, 
    10}}, rotation = 0)));
    HeatTransfer.Interfaces.HeatPort_b port_b 
    annotation(Placement(visible = true, transformation(origin = {100, 
    0}, extent = {{-10, -10}, {10, 10}}, rotation = 0), 
    iconTransformation(origin = {62, 0}, extent = {{-10, -10}, {10, 
    10}}, rotation = 0)));
    HeatTransfer.Celsius.TemperatureSensor temperatureSensor 
    annotation(Placement(visible = true, transformation(origin = {58, 
    52}, extent = {{-10, -10}, {10, 10}}, rotation = 0)));
    Modelica.Blocks.Interfaces.RealOutput temperature 
    annotation(Placement(visible = true, transformation(origin = {106, 
    52}, extent = {{-10, -10}, {10, 10}}, rotation = 0), 
    iconTransformation(origin = {0, -102}, extent = {{-10, -10}, {10, 
    10}}, rotation = -90)));
    
    equation
    
    connect(thermalConductorOuter.port_b, heatCapacitor.port) 
    annotation(Line(points = {{-38, 0}, {2, 0}, {2, -10}}, color = 
    {191, 0, 0}, smooth = Smooth.Bezier));
    
    connect(thermalConductorInner.port_a, heatCapacitor.port) 
    annotation(Line(points = {{38, 0}, {2, 0}, {2, -10}}, color = 
    {191, 0, 0}, smooth = Smooth.Bezier));
    
    connect(port_a, thermalConductorOuter.port_a) 
    annotation(Line(points = {{-100, 0}, {-74, 0}}, color = {191, 0, 
    0}));
    
    connect(thermalConductorInner.port_b, port_b) 
    annotation(Line(points = {{74, 0}, {100, 0}}, color = {191, 0, 
    0}));
    
    connect(temperatureSensor.port, heatCapacitor.port) 
    annotation(Line(points = {{48, 52}, {2, 52}, {2, -10}}, color = 
    {191, 0, 0}, smooth = Smooth.Bezier));
    
    connect(temperatureSensor.T, temperature) annotation(Line(points = 
    {{68, 52}, {106, 52}}, color = {0, 0, 127}));
    annotation(Icon(graphics = {Rectangle(origin = {-1.75, -0.54}, 
    fillColor = {142, 142, 142}, fillPattern = FillPattern.Backward, 
    extent = {{-63.75, 99.46}, {63.75, -99.46}}), Text(origin = {-3, 
    83}, lineColor = {85, 0, 255}, extent = {{-59, 25}, {59, -25}}, 
    textString = "%name"), Text(origin = {-15, -83}, lineColor = {170, 
    0, 0}, extent = {{-13, 21}, {13, -21}}, textString = "T"), 
    Text(origin = {-34, 2}, extent = {{-20, 12}, {20, -12}}, 
    textString = "outer"), Text(origin = {29, 2}, extent = {{-27, 10}, 
    {27, -10}}, textString = "inner"), Text(origin = {-2, 57}, extent 
    = {{-60, 19}, {60, -19}}, textString = "C=%heat_capacity"), 
    Text(origin = {22, 33}, extent = {{-84, 25}, {84, -25}}, 
    textString = "G=%thermal_conductance")}));
    
    end Wall;
    
    

• Validation

  • package.mo

  within GreenEnergy;
  package Validation
  extends Modelica.Icons.ExamplesPackage;
  end Validation;
  

  • Wall.mo

  within GreenEnergy.Validation;
  
  model Wall
  
    extends Modelica.Icons.Example;
  
    GreenEnergy.HeatTransfer.Components.Wall wall1(area = 1, 
     density(displayUnit = "kg/m3") = 1, initial_temperature = 
     274.15, 
     specific_heat_capacity = 1, thermal_conductivity = 1, thickness 
     = 1)
  
     annotation(Placement(visible = true, transformation(origin = 
     {0, 0}, 
     extent = {{-45, -45}, {45, 45}}, rotation = 0)));
  
    //Modelica.Thermal.HeatTransfer.Sources.FixedTemperature 
    fixedTemperature(T = 283.15)  annotation(
    //Placement(visible = true, transformation(origin = {-76, 22}, 
    extent = {{-10, -10}, {10, 10}}, rotation = 0)));
  
    //Modelica.Thermal.HeatTransfer.Sources.FixedTemperature 
    fixedTemperature1(T = 303.15)  annotation(
    //Placement(visible = true, transformation(origin = {68, 22}, 
    extent 
    = {{-10, -10}, {10, 10}}, rotation = 180)));
  
    Modelica.Thermal.HeatTransfer.Sources.FixedTemperature 
    fixedTemperature annotation(Placement(visible = true, 
    transformation(origin = {-70, -0}, extent = {{-10, -10}, {10, 
    10}}, 
    rotation = 0)));
  
    Modelica.Thermal.HeatTransfer.Sources.FixedTemperature 
    fixedTemperature1 annotation(Placement(visible = true, 
    transformation(origin = {70, 0}, extent = {{-10, -10}, {10, 
    10}}, 
    rotation = -180)));
  
    equation
  
    connect(fixedTemperature.port, wall1.port_a) 
    annotation(Line(visible 
    = true, origin = {-44.85, -0}, points = {{-15.15, -0}, {15.15, 
    0}}, 
    color = {191, 0, 0}));
  
    connect(wall1.port_b, fixedTemperature1.port) 
    annotation(Line(visible = true, origin = {43.95, 0}, points = 
    {{-16.05, 0}, {16.05, 0}}, color = {191, 0, 0}));
  
    end Wall;
  
  

And then I am trying to run Validation.Wall model... So, why I am receiving error that component is not found in scope?

Best

The problem is in the next packages code:

extends Modelica.Thermal.HeatTransfer;

and

extends Modelica.Thermal.HeatTransfer.Components;

When I replaced those lines with the simpler line:

extends Modelica.Icons.Package;

Problem disappeared.

Modelica.Thermal.HeatTransfer package contains those lines at the beginning:

within Modelica.Thermal;

but Modelica.Icons.Package is declared in a different way by using partial keyword. More details about partial keyword here.

Best.