Fail to mock property on MockObject

/// <summary>
        ///A test for mocking property getter from .Net Framework class
        ///</summary>
        [TestMethod()]
        public void BoolPropertyGetterFromNetFxTest()
        {
            MockManager.Init();

            // ActiveDirectoryAccessRule is the class to be mocked.
            MockObject mock = MockManager.MockObject(typeof(ActiveDirectoryAccessRule),
                new SecurityIdentifier("S-1-5-32-545"),
                ActiveDirectoryRights.ReadProperty,
                AccessControlType.Allow,
                Guid.Empty, ActiveDirectorySecurityInheritance.All);
            mock.ExpectGetAlways("IsInherited", true);

            ActiveDirectoryAccessRule rule = (ActiveDirectoryAccessRule)mock.Object;
            Assert.IsTrue(rule.IsInherited, "Failed to mock IsInherited");

            MockManager.Verify();
        }

        /// <summary>
        /// A test for mocking property getter from my own code
        /// </summary>
        [TestMethod()]
        public void BoolPropertyGetterFromOwnCodeTest()
        {
            MockManager.Init();

            MockObject mock = MockManager.MockObject(typeof(MyClass));
            mock.ExpectGetAlways("BoolProperty", true);

            MyClass myObj = (MyClass)mock.Object;
            Assert.IsTrue(myObj.BoolProperty, "Failed to mock my own proeprty");

            MockManager.Verify();
        }

    /// <summary>
    /// Class of property getter
    /// </summary>
    public class MyClass
    {
        private bool _myBool;

        public MyClass()
        {
            _myBool = false;
        }

        public bool BoolProperty
        {
            get { return _myBool; }
        }
    }