如何将对象列表转换为对象在VB.net中实现的接口列表？

I am working in VB.net and have a Class, Foo, that implements an interface, IBar. I have a List of Foo's, but I need to pass a list of IBar's into a function, but I keep getting casting errors, even when I use DirectCast. My code isI am working in VB.net and have a Class, Foo, t