Vista - Calling List<T>.AddRange with Reflection.Emit

I've been looking everywhere on how to call AddRange Method of a
List<myClass> field in Reflection.Emit
My code goes like this

MethodInfo method =
typeof(List<>).MakeGenericType(typeof(myClass)).GetMethod("AddRange",
BindingFlags.Instance | BindingFlags.Public, null, new Type[] {
typeof(IEnumerable<>).MakeGenericType(typeof(myClass)) }, null));

and then the implementation

ilgen.Emit(OpCodes.Ldfld, reflectionField);
ilgen.Emit(OpCodes.Ldarg_1);
ilgen.Emit(OpCodes.Callvirt, method);

on this last line I get a NotSupportedException with message: "Specified
method is not supported."

I'm pretty sure my methodinfo needs a modification but I don't know what to
do.
Please guide me to the right place or post the right method info that i need
to specify for this to work.