Android app built in release mode crash by missing default constructor

My Android app crashes when built in release mode. (in debug mode it is OK!)

[AndroidRuntime] java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
[AndroidRuntime] at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
[AndroidRuntime] Caused by: java.lang.reflect.InvocationTargetException
[AndroidRuntime] at java.lang.reflect.Method.invoke(Native Method)
[AndroidRuntime] at java.lang.reflect.Method.invoke(Method.java:372)
[AndroidRuntime] at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
[AndroidRuntime] ... 1 more
[AndroidRuntime] Caused by: md52ce486a14f4bcd95899665e9d932190b.JavaProxyThrowable: System.MissingMethodException: Default constructor not found for type DbGuide.MenuCell

It has default constructor anyway:

public class MenuCell : ImageCell
    {
        public MenuCell () : base()
        {
            this.TextColor = Color.White;
        }
    }

What should I do?

Thanks in advance!