Have a MICS 7.1 w/ exts. 1100 thru 1199. Upgrade from Startalk to CP 150. When I go to build the mboxes it will let me create mboxes w/ 12XX, 13XX, 10XX ect. but when I try 11XX it says "invalid" mbox. Initialized the unit multiple times and I get the same thing! Any ideas ????