Puzzling **ERROR: inconsistent sizes of data regions

[hengkek@xxxxxxxxxx]

Greetings

I'm getting a puzzling error:

 *** NOTE: Ambiguous coordinates on X axis: EV[D=1]-EV[D=2]
 **ERROR: inconsistent sizes of data regions: X axis
          EV[D=2] has 134 points (I=000:133)
          expression has 133 points (I=001:133)

Both my datasets have 133 points and are identical in terms of grid and
axes, but I'm puzzled as to how it becomes 134 in the 2nd data set as
reported by the error above.

Any clues how to correct this?

My paraphrased session is appended.
Thanks for any answers.

-chk
Physical Oceanography
Singapore

-------- Start my session ------------------
 ! NOAA/PMEL TMAP
 ! FERRET v5.51
 ! Solaris 5.8 - 02/28/03
 ! 30-Jul-03 16:25
yes? use "aaa.nc"
yes? use "bbb.nc"
yes? let var_diff=ev[d=1]-ev[d=2]
 !-> DEFINE VARIABLE var_diff=ev[d=1]-ev[d=2]
yes? fill/l=2 var_diff
 *** NOTE: Ambiguous coordinates on X axis: EV[D=1]-EV[D=2]
 **ERROR: inconsistent sizes of data regions: X axis
          EV[D=2] has 134 points (I=000:133)
          expression has 133 points (I=001:133)
yes? show dat
     currently SET data sets:
    1> aaa.nc
 name     title                       I         J         K        L
...[deleted]...
 EV      surface elevation          1:133     1:199     ...       1:21
 
    2> bbb.nc  (default)
 name     title                       I         J         K        L
...[deleted]...
 EV      surface elevation          1:133     1:199     ...      1:21
-------- end my session ------------------