Class Extension is not initiated/called in Graph Extension

UPDATE:

I added the below code to my Graph Ext.

public override void Initialize()
{
    base.Initialize();
    HCLEmployeeCostEngine = new HCLEPEmployeeCostEngine(Base);
}

I also tried overriding “GetOvertimeMultiplier” as follows:

[PXOverride]
public override decimal GetOvertimeMultiplier(string earningTypeID, Rate employeeRate)
{
	// Do some stuff
	base.GetOvertimeMultiplier(earningTypeID, employeeRate);
}

The Base is not null anymore but still the overridden method “GetOvertimeMultiplier” in the Class Ext “MyEmployeeCostEngineExt” is not called.

@aaghaei EmployeeCostEngine is not a PXGraph. The PXOverride only works for graphs.

Thank you @Dmitrii Naumov for the clarfification but even by removing the [PXOverrode] still my overridden method is not called. Here is the little class override as I have it now. Any thoughs why the override is not executed?

using System;
using PX.Data;
using PX.Objects.EP;

namespace MyProject
{
    public class MyEmployeeCostEngineExt : EmployeeCostEngine
	{
		public MyEmployeeCostEngineExt(PXGraph graph) : base(graph) { }

		public static bool IsActive() => true;

		public override decimal GetOvertimeMultiplier(string earningTypeID, Rate employeeRate)
		{
			// Do some stuff
			base.GetOvertimeMultiplier(earningTypeID, employeeRate);
		}
	}
}

@aaghaei I think you need to override 

public virtual EmployeeCostEngine CreateEmployeeCostEngine()

from TimeCardMaint and return your overridden EmployeeCostEngine class from there. 

That should do the trick.

BTW, instead of writing code in the graph extension constructor, you can override Initialize method, which server the same purpose but already has Base graph defined. 

Thank you for the response @Dmitrii Naumov Below code is my underestanding of your comments but still I can’t make the Acumatica framework to call the “GetOvertimeMultiplier” override. Any idea what else I am missing here and any chance if you kindly try to see if you can make it work?

using System;
using System.Collections;
using PX.Data;
using PX.Objects.EP;

namespace MyProject
{
    public class MyTimeCardMaintExt : PXGraphExtension<TimeCardMaint>
    {
        public static bool IsActive() => true;

        public MyEmployeeCostEngineExt MyEmployeeCostEngine;

		public override void Initialize()
		{
			base.Initialize();
			MyEmployeeCostEngine = new MyEmployeeCostEngineExt(Base);
		}

        public delegate IEnumerable ReleaseDelegate(PXAdapter adapter);

        [PXOverride]
        [PXButton]
        public virtual IEnumerable Release(PXAdapter adapter, ReleaseDelegate baseMethod)
        {
			// Do some stuff
            return baseMethod?.Invoke(adapter);
        }


		public class MyEmployeeCostEngineExt : EmployeeCostEngine
		{
			public MyEmployeeCostEngineExt(PXGraph graph) : base(graph) { }

			public override decimal GetOvertimeMultiplier(string earningTypeID, Rate employeeRate)
			{
				// Do some stuff
				base.GetOvertimeMultiplier(earningTypeID, employeeRate);
			}
		}
    }
}

@Dmitrii Naumov I really appreciate your help. The overriden class is called when I override the CreateEmployeeCostEngine(). Thanks again.