You can use the Designer to add a ScrollView to a layout but you cannot use the Designer to add any other View to the ScrollView.
All Views added to a ScrollView must be added in code.
Look at your layout in the Designer, select your ImageView and look at it's Parent property in the Designer.
You'll see that it's Parent is NOT the ScrollView.
It's Parent is likely to be the Activity itself or the Panel that you added to your layout.
So remove the ImageView from your layout and then in your code you need to create an ImageView and add it to the ScrollView.
Martin.