How to get optional fields to work?

[richardba]

I have created a definitions file for a project, but I can't put a field as optional, this is what I'm trying

  ---@param object any
  ---@param name string
  ---@param position Vec3
  ---@param rotation? Rotation
  ---@param roomID? integer
  ---@param animNumber integer
  ---@param frameNumber integer
  ---@param hp integer
  ---@param OCB integer
  ---@param AIBits? table
  ---@return Moveable
Moveable = function (object, name, position, rotation, roomID, animNumber, frameNumber, hp, OCB, AIBits) end

however when I'm using it in my actual code I'm getting

This function requires 9 argument(s) but instead it is receiving 8.Lua Diagnostics.(missing-parameter)

what am I doing wrong?