[ferret_users] time axis error

[Izidine Pinto <izidinep@xxxxxxxxx>]

Dear ferrets users
Iam trying to do the difference between two variables and I am having the following error.
How can I solve this?

 currently SET data sets:
    1> ./eca_etr.moz.daily.1981_1999.echama2.nc

 name     title                             I         J         K         L
 INTRA_PERIOD_EXTREME_TEMPERATURE_RANGE
          Difference between the absolute  1:52      1:87      1:1       1:1
 
    2> ./eca_etr.moz.daily.2031_2049.echama2.nc  (default)

 name     title                             I         J         K         L
 INTRA_PERIOD_EXTREME_TEMPERATURE_RANGE
          Difference between the absolute  1:52      1:87      1:1       1:1
 
yes? fill INTRA_PERIOD_EXTREME_TEMPERATURE_RANGE[d=2]-INTRA_PERIOD_EXTREME_TEMPERATURE_RANGE[d=1]

 *** NOTE: Ambiguous coordinates on T axis: INTRA_PERIOD_EXTREME_TEMPERATURE_RANGE[D=2]-INTRA_PERIOD_EXTREME_TEMPERATURE_RANGE[D=1]
 **ERROR: illegal limits: INTRA_PERIOD_EXTREME_TEMPERATURE_RANGE does not exist at T=02-MAR-1999 12:00

          Axis extremes are T=02-MAR-1999 12:00


Any help is strongly appreciated
-- 
I.P.
:-)