GRIB I/O Error: Bit Map I/O

[Rick Brandt]

Greetings GrADSUSR listserv,

I have run into an error, and I cannot determine the cause.  I downloaded
the .ctl, .grb, and .idx files from NCEP after requesting only the 500-mb
geopotential heights.  The .ctl file has been modified to include only the
pertinent variable.

My .ctl file is:

dset  ^narr-a_221_19790601_0000_000.grb
index ^narr-a_221_19790601_0000_fff.idx
undef 9.999E+20
title Daily North American Regional Reanalysis - (8) 3hr time steps
*
*  produced by grib2ctl v0.9.12.5p33h modified by hand v1.0 WNE
*  use gribmap -0 -i sample.ctl
*
dtype grib 221
options template
*
pdef 349 277 lcc 1 -145.5 1 1 50 50 -107 32463 32463
* pdef 349 277 bilin sequential binary-
little /nomads3_data/raid5a/data/merged_AWIP32/grid221.pdef
xdef 586 linear -220 0.375
ydef 240 linear 0 0.375
tdef 8 linear 00z01jun1979 3hr
zdef 1 levels 500
vars 1
HGTprs    1    7,100,0 anl Geopotential height [gpm]
ENDVARS

I can open the .ctl file ('open <filename>') with no problem, but when I
try to display the Geopotential height (HGTprs), I get the following error:

Notice:  Automatic Grid Interpolation Taking Place
GRIB I/O Error: Bit Map I/O
Data Request Error: Error for variable 'HGTprs'
  Error ocurred at column 1
DISPLAY error: Invalid expression
  Expression = HGTprs

I searched the archives and found several others who wrote the listserv
with the same error, but I did not see any responses.  Thanks in advance
for any help.

Rick Brandt