How to use the InvokeMethod activity to add a string to a generic list using Workflow Foundation 4

I have a Workflow Foundation 4 activity that has a InvokeMethod that is configur开发者_JAVA百科ed to call the Add method on an instance of type IList(Of String), providing a parameter of type String.

Running it gives me this error though:

'IList`1' does not have a public instance method named 'Add' matching the parameter
types, generic type arguments, and generic type constraints supplied to InvokeMethod
'InvokeMethod'.

I've tried all settings for the InvokeMethod activity I could think of, to no avail.

So the question is: how do I make the InvokeMethod add the string parameter to the generic list?

Why not use the AddToCollection activity?