Dvd disc not playing

i have a 321 GS Series II BOSE Sony DVD Home Entertainment System -
the movie DVDs i buy play in my system.

i burned a photo DVD on my computer and it does not play in my 321 system.
disc i burned does play in a cheap dvd player i have.

the 321 manual says make sure the Region Code matches the disc i burn. it is Region I Code according to the bottom of the system.

i am using HP dvd+r 16x to burn the photos. why is this disc not working on my BOSE system.

please advise.
thx.

aj