I tried the following formula but it retrieved NA:
ek.get_timeseries(rics=['MPAA.O'], fields=['NDA_RAW.Nda_date','NDA_RAW.Nda_volume'], start_date='2005-01-01',end_date= '2005-03-22', interval = 'daily')
Your colleague advised me usind NDA_RAW.Nda_volume because it is more accurate than other indicators of volume.