Whoa, session stuffage

Can anyone explain this...?

session_start();
if (!isset($photo))
{
  # hits here first time only, then skips as it should
  $photo = new Photo;
  session_register("photo");
}
#works
$photo->m_Name = "something";

# works
echo $photo->m_Name;

# Undefined function!
$photo->LoadSelfFromDatabaseByAdID($id);
# Works
$photo->Clear();

$photo = new class_photo;

# Works!
$photo->LoadSelfFromDatabaseByAdID($id);
# Works
$photo->Clear();

Why do the member variables work okay but the
function calls are off?  I've shut down the sessions fully via
exiting the browser, and tried other methods which work.
My calls are all the same, I've tried swapping the order of
the includes, and the functions themselves in the file to see
if it changes, but it follows that function.  Is there a max
namespace on session-registered methods off of a class?

After all the PHP at night, I actually ENJOY going to work
and back to my nice world of COM/DCOM and C++. *wink*
Okay, maybe not the COM/DCOM part. =)

-Szii