Adding element to List through reflection

I try to add an element to a List I retrieved through reflection.

The following line

property.PropertyType.GetMethod("Add").Invoke(entity, new[] { innerValue });

is throwing an error

Object does not match target type" (Reflection.TargetException)

But the Types should match:

string listType=property.PropertyType().FullName; // System.Collections.Generic.List`1[[My.Entities.Task, My.Entities, Version=1.4.6429.20475, Culture=neutral, PublicKeyToken=null]]
string elementType=innerValue.GetType().FullName; // My.Entities.Task

entity is an object that contains the property above

What is wrong here?