I'm gonna make a guess here and I'm sure I'll be corrected by the pros if I'm off~ DeviceLock shouldn't be removed, just deactivated. Further, I believe that OnLock still needs DeviceLock to actually do it's thing. OnLock is just a more customizable GUI that uses the OEM lock to lock the phone.
Are you using the most recent version of OnLock?
http://pdaphonehome.com/forums/ppc-6...tml#post600776