>I have an object with some properties.... In the debug i can see al properties, but when i use amembers it returns an incorrect number....11 instead the real number of properties contained in the object... Look at the image where you can see all the properties and the the amembers() result...

Amembers without any flags would only return info for public properties.
Another reason for it to return 11 is that you are not using mdot prefix.