You have attempted to begin using the instrument before it has fully warmed up.
Wait until the instrument finishes its warm-up period (approximately 30 minutes). The Frame Temperature status on the Signal Display screen will read "OK" when the instrument is ready to be run. Then press Continue to retry the calibration or Exit to abort the calibration.
The air bearing gas pressure may be too low. The DMA cannot start, move or measure. The instrument must be operated with the appropriate air bearing gas pressure.
Set the air bearing gas pressure to a minimum of 60 psi. Check that the Air Pressure status on the Signal Display screen reads "OK." Then press Continue to retry the calibration or Exit to abort the calibration.