When I set phatty’s arp CLK SRC: MIDI, LOgic 9 will NOT drive the phatty’s Arp. Logic9 IS set to send midi clock under it’s “synchronization” settings. Just silence.
help please 
best,
SvK
CLK SRC is a setting you can do both global and per preset. It allows you to have a “standard” setting as well as deviations (is that the correct english word?) for individual presets.
If you set it to GLOBAL in the ADVANCED PRESET menu, you have to set CLK SRC to MIDI in the global settings.
If you set it to MIDI in the ADVANCED PRESET menu, the global setting doesn’t matter (for that preset).
If that doesn’t help you, spend a bit more time poking around with Logic (unless you’ve got it nailed and have sent clock to other devices in the past). I don’t have 9 (I have 
and it’s crap (misleading). I think you’ll need to send clock and realtime (forget what it’s called) so that start/stop are sent as well.
My biggest gripe with it is that it (Logic) won’t slave to an external clock, at least not the version I have. I have to guess that 9 is better.
You have to turn on MIDI clock send in Logic and specify the output that it’s going to. It’s under preferences and then “synchronization,” I believe. Logic doesn’t automatically transmit any sync until you turn it on.