early 909 versions are notorious for not slaving to clock. they prefer being the master.
guys on ebay sell a version 4 eprom that apparently fixes the timing issue for around AU$35. to see what version your 909 has, power off, then hold down the track 1 button and power on. LEDs 1-4 will light according to the version you have.
i just use the 909 as master to sample a few patterns it into the OT, then i disconnect the 909 and connect my other synths and let OT be the master.