This could happens if you use a parameter to your function as a panel, entity, string or something.
This isn't working...
Code:

---

function (p_entity)
{
  p_entity.x = 10;
}
Code:

...but this should work...
Code:

function (e_entity)
{
  you = e_entity;
  your.x = 10;
}

...or this is also working...
Code:

entity* e_pointer;
function (e_entity)
{
  e_pointer = e_entity;
  e_pointer.x = 10;
}