[gembud] adding info to tables

good morning,
I'm trying to muddle my way creating images using the experimental snow probability gribs from the HPC
ftp://ftp.hpc.ncep.noaa.gov/pwpf/conus/pwpf_24hr/

using dcgrib2 to convert to gem I get the following

[2213] 110116/1224[GB 1]  No GEMPAK parameter name defined for this grid.
[2213] 110116/1224[DECODE_GRIB2 -34] Could not determine parameter name 0 1 29 
9 [0]
[2213] 110116/1224[GB 1]  No GEMPAK parameter name defined for this grid.
[2213] 110116/1224[DECODE_GRIB2 -34] Could not determine parameter name 0 1 29 
9 [0]
[2213] 110116/1224[GB 1]  No GEMPAK parameter name defined for this grid.
[2213] 110116/1224[DECODE_GRIB2 -34] Could not determine parameter name 0 1 29 
9 [0]
[2213] 110116/1224[GB 1]  No GEMPAK parameter name defined for this grid.
[2213] 110116/1224[DECODE_GRIB2 -34] Could not determine parameter name 0 1 29 
9 [0]
[2213] 110116/1224[GB 1]  No GEMPAK parameter name defined for this grid.
[2213] 110116/1224[DECODE_GRIB2 -34] Could not determine parameter name 0 1 29 
9 [0]
[2213] 110116/1224[GB 1]  No GEMPAK parameter name defined for this grid.
[2213] 110116/1224[DECODE_GRIB2 -34] Could not determine parameter name 0 1 29 
9 [0]
[2213] 110116/1224[GB 1]  No GEMPAK parameter name defined for this grid.
[2213] 110116/1224[DECODE_GRIB2 -34] Could not determine parameter name 0 1 29 
9 [0]
[2213] 110116/1224[DC 5]  Normal termination.
[2213] 110116/1224[DC 2]  Number of bulletins read and processed: 7
[2213] 110116/1224[DC 6]  Shutting down.

looking at that, studying the 'tables/grid/g2varswmo2.tbl' using DeGRIB I added the following to the g2varswmo2.tbl

000 001 029 009 24 hr Prob of Total snowfall     %                    
ProbASNOW24      ?  -9999.00

well now no errors in the log, it does create the gem file
but when I do a gdinfo on it... the output file is empty
so something isn't correct
do I need to add the definition somewhere else ??

thanks
-Jeff