ANOTHER Garmin 305 question - setting pace alarm

Last night I was trying to set a "custom" training pace - set it for 8:45 and 9:05 minutes - on my long run tomorrow I want to be at that range... but when I save it - it resets one value each time...I guess my range is not "acceptable" for training? i could not find anything in the manual to help me on this...any ideas?