List of Objects in Boo

Hey Guys, I'm wondering why I can't add values to my List, It works if the class isn't self defined for example:

 private newVertices as List[of Vector3] = List[of Vector3]()
 newVertices.Add(Vector3(x, y, (z + 1)))

but not this way: import UnityEngine

 public class BlockTexture(): // function parameters are the position in the texture
     def constructor(_top as int, _north as int, _east as int, _south as int, _west as int, _bottom as int):
         top    = _top
         north  = _north
         east   = _east
         south  = _south
         west   = _west
         bottom = _bottom
 
 public class Block():
     def constructor(_name as string, _texture as List ):
         id      = len(Blocks.blockList)
         name    = _name
         texture = _texture
 
 public static class Blocks (MonoBehaviour): 
 
     public blockList as List[of Block] = List[of Block]()
     
     def getBlockById(id):
         return blockList[id]
     
     blockList.Add( Block("Stone", BlockTexture(0, 0, 0, 0, 0, 0) ) )

Is there any way to append to such a list? (And please don't tell me that BOO is a bad language! That's not what I'm asking for.)

Thanks in advance!