Animate custom type property

Hi, i trying to animate variable (for example) myClass of "MyClass" type with ObjectReferenceKeyframe in "MyComponent : MonoBehaviour",
MyClass with Serializable attribute,
editorCurveBinding. propertyName = "myClass";
editorCurveBinding. type = typeof(MyComponent);
so, animation successfully created via script, but playing this animation do not affect on myClass variable, its not changed, in Animation window property marked as "Missing" and i can't add it with "Add Property" button (property not shown in list) but same thing works with Sprite type, how can i use "MyClass" type this way? is it possible? Thx!