Form back command not working. Getting Kern_Exe3 error

[Basit781]

Hi to all,
Hope you all will be fine. I created a form with SoftKey Options and Back. I am following this tutorial. Although i didn't create form with Ui Designer. But i want that when back key is pressed the view changes. But it doesn't happen.

http://symbianodessey.com/?p=122

Here is my code

/**
 * Handle a button press and tell whether it closes the dialog.  (override)  
 * @param aButtonId the identifier for the button (avkon.hrh)
 */
TBool CL3_Mazazeek_AssignDefaultToneScreen_ViewContainer::OkToExitL( TInt aButtonId )
	{
	
	
	if ( aButtonId == EAknSoftkeyBack )
		{
		if ( CAknForm::OkToExitL( EAknSoftkeyBack ) )
			{
			iCommandObserver->ProcessCommandL( EEikCmdExit );
			//iCommandObserver->ProcessCommandL( EAknSoftkeyBack );
			return EFalse;
		
		   
			}
		else
			{
			return EFalse;
			}
		}
	
	// The 'exit application on close' property automatically adds code to exit the 
	// application when the right soft key is pressed. If this property is set to false, 
	// and AddToStackL has been called on the Form object (e.g., it was not shown as a dialog), 
	// code must be added manually to avoid a panic when exiting the application.
	return CAknForm::OkToExitL( aButtonId );
	}

void CL3_Mazazeek_AssignDefaultToneScreen_View::ProcessCommandL(TInt aCommand) {
	
	if (aCommand == EAknCmdExit)
	//if (aCommand == EAknSoftkeyBack)
			{
			AppUi()->ActivateLocalViewL(TUid::Uid(EL2MazazeekScreenViewId));
			return;
			}
		CAknView::ProcessCommandL(aCommand);
	
}

But nothing happening. View is not changing. Please tell me what i am doing wrong.

Thanks