Variable define and/or aave oddity

[Colleen Mikovitz]

I am working though a script to do simple global maps of variables
with annotations of the global average.  But I noticed that when I use
the define command,  aave returns a different value on that newly
defined variable than on the original variable.  I just installed the
newest release to see if that would correct it, but I get the same
thing.

Could someone look at the following to see if I am doing anything odd
or if this is a known/unknown problem?

Thanks,
Colleen

*********************
ga-> q config
Config: v2.0.a7.1 little-endian readline printim grib2 netcdf hdf4-sds
hdf5 geotiff
Grid Analysis and Display System (GrADS) Version 2.0.a7.1
Copyright (c) 1988-2009 by Brian Doty and the
Institute for Global Environment and Society (IGES)
This program is distributed WITHOUT ANY WARRANTY
See file COPYRIGHT for more information.

Built Fri Aug  7 18:15:20 EDT 2009 for i386-apple-darwin9.7.0

ga-> q ctlinfo
dset /Users/colleen/lib/sfcdn_new.binary
title GLW
undef -999
xdef 360 linear 0.5 1
ydef 180 linear -89.5 1
zdef 1 linear 1000 1
tdef 1 linear 00Z01JAN2002 180mn
vars 1
prop  1  0  check var
endvars


ga-> d prop
Contouring: 100 to 450 interval 50
ga-> define newvar=prop
Define memory allocation size = 527072 bytes
ga-> d aave(prop,g)
Result value = 335.076
ga-> d aave(newvar,g)
Result value = 324.465
ga-> d prop-newvar
Constant field.  Value = 0