AutoCAD .NET :: How To Code Drop-down List For Custom Property Using OPM

I am mainly developing for AutoCAD 2013/2014 how to implement a custom property as a drop-down list using OPM and .NET/C# wrapper. I have successfully created categorized custom properties already and can read/save them in XRecords via the OPM. I further implemented the members for IDynamicEnumProperty (using an ObjectARX DLL) in .NET/C# which are:

// ENUM-PROPERTY INTERFACE METHODS DEFINITIONenum myEnum{ steel = 0, copper, wood};public void GetNumPropertyValues( int numValues ){ numValues = 3;}public void GetPropValueName( int index, out String valueName ){ valueName = Enum.GetName(typeof(myEnum), index);}public void GetPropValueData( int index, ref Object valueName ){ valueName = index;}

And I have implemented the GetCurrentValueData() and SetCurrentValueData() members in my .NET/C# wrapper as per the IDynamicProperty2 interface as following:

public void GetCurrentValueData( Object pUnk, ref Object varData ) {AcadObject obj = pUnk as AcadObject; if ( obj != null ){using ( Active .Document.LockDocument( DocumentLockMode.ProtectedAutoWrite, null, null, true ) ){using ( var tr = Active.Transaction ){ObjectId ObjId = new ObjectId( (IntPtr) obj.ObjectID ); DBObject DbObj = tr.GetObject( ObjId, OpenMode.ForRead ); if ( DbObj != null ){try {if (
[code]....

This code compiles without error but instead of the expected drop-down list the OPM only shows a field where I can enter or edit integer numbers, but there is no drop-down list when clicking on the field....