Hello,
The UUID is the way SIM uses to link the ILO to the server and as far as I know can not be change to use the serial instead. You need to regenerate your UUID on the affected servers, a how to can be found in the onon hp link below.
http://www.kozeniauskas.com/itblog/2011/01/23/no-uuid-or-serial-number-on-hp-server/
