It looks like "own_window_hints" is missing, no?
EDIT: your "own_window_hints" is there, but is separated from the values by another line... maybe that's the problem.
This is what I have in my conky.conf, although this is for xfce:
The "own_window_type" option is commented. There might be a type that does almost the same as specifying those hints, but I think this yielded the best results.
I remember it working fine in fluxbox, but I'm not sure if I used these same options. Never got the transparency to work properly on kde, though...