Cast generic class to interface

I have a problem with casting a generic class to the interface it is implementing.

My code is like this:

interface foo
{
    void foobar();
}

class bar: foo
{
    public void foobar()
    {
        throw new NotImplementedException();
    }
}

now I have my factory that creates instances of my classes by the interface, mostly a simple microkernel (service locator). I will simplify it here. Normally it will look up the implementing class from the configs and the factory take the type as T but that doesn't matter for the problem I have.

public static class Factory
{


    public static Lazy<foo> CreateLazyInstance()
    {
        Lazy<foo> instance;


        Type type = typeof(bar);

        Type lazyType = typeof(Lazy<>);
        Type toContruct = lazyType.MakeGenericType(type);

        instance = (Lazy<foo>)Activator.CreateInstance(toContruct);

        return instance;
    }
}

If will fail at:

instance = (Lazy<foo>)Activator.CreateInstance(toContruct);

and claim with an InvalidCastException that it is not possible to cast the type Lazy<bar> to Lazy<foo>.

Is there any way to tell the CLR that this cast will work or to workaround this problem?

Copyright License：
Author:「Kolja」,Reproduced under the CC 4.0 BY-SA copyright license with link to original source & disclaimer.
Link to：https://stackoverflow.com/questions/7310530/cast-generic-class-to-interface