You don't seem to have passed a List<add> to the view, so you get the error that you do. Your Razor code doesn't check to see if it actual got an IList<add> object. You just assume that you do and you start trying to get elements from a collection that doesn't even exist so the call to .Count with throw the exception you're seeing.
This is the easiest error to track down using the debugger. You better get to know the debugger very well because it a tool to debug YOU. It's there so you can investigate and understand your code. The reason you have the error in the first place is because you're just guessing at what you're code is doing instead of learning about it and understanding it.
I can't tell you why the Razor code didn't get a collection because you didn't show the code that builds the collection and passes it to the view.
If you don't know how to pass an object to a view, you REALLY need to go back to learning the basics of MVC. This is beginner level stuff here.