ENS_PROB question

Hello,

I'm trying to calculate the probability of exceedance for a 12 member ensemble. 
My script is appended. When running this script I get:
 [DE 4]  Number of MEMBERS = 12
 Grid file: 
{namm,gfsm,srefn1m,srefn2m,srefp1m,srefp2m,namw,gfsw,srefn1w,srefn2w,srefp1w,srefp2w}
 GRID IDENTIFIER:
    TIME1             TIME2         LEVL1 LEVL2   VCORD PARM
060211/1200F036                         0          NONE EXX__1
 GAREA:     37;-80;45;-68                                                       
       SCALE:  0
 MINIMUM AND MAXIMUM VALUES     0.00     1.00
 LINE CONTOURS:
 LEVELS:         0.00

BUT nothing but a blank map

So looking closer at the ENS_PROB, I saw it is actaully a multivariate 
function. So to make it work, I thought I needed two conditions - in this case 
PTOT>25 but <150 or GFUNC = ENS_PROB(AND(GT(PTOT,25),LT(PTOT,150))
Upon runing this I get.

[DE -5]  No ensemble file referenced in ensemble diagnostic.
 [DG -70]  Ensemble field cannot be computed.

What am I mising?
Thanks!
Dave
________________

#!/bin/tcsh

# probability of exceedance model precip
# 1 panel


set g1 = 'namm'
set g2 = 'gfsm'
set g3 = 'srefn1m'
set g4 = 'srefn2m'
set g5 = 'srefp1m'
set g6 = 'srefp2m'
set g7 = 'namw'
set g8 = 'gfsw'
set g9 = 'srefn1w'
set g10 = 'srefn2w'
set g11 = 'srefp1w'
set g12 = 'srefp2w'

set device = xw
#set device = gf
#set device = "ps||8.5;11|c"
set time = '060211/1200F036'

nice gdcntr << endgdcntr
 GDATTIM  =  $time
 GLEVEL   =  0
 GVCORD   =  none
 GFUNC    = ENS_PROB(GT(PTOT,25))
 GDFILE   = {$g1,$g2,$g3,$g4,$g5,$g6,$g7,$g8,$g9,$g10,$g11,$g12}
 CINT     =  1
 LINE     =  3
 TITLE    =  1// ^
 DEVICE   =  $device
 PROJ     =  mer
 garea    = 37;-80;45;-68
 CLEAR    =  y
 clrbar = 1/V///.75;.02/
 SCALE    =  0
 PANEL   
 TEXT     =  1
# FINT     = 25;50;75;100;125;150;175;200;225
 FINT     = 5;10;15;20;25;30;35;40;45;50;55;60;65;70
# FINT     = 4;8;12;16;20;24;28;32;36;40;44;48
 FLINE    = 0;26;4;24;21;22;23;20;17;13;14;11;10;9
 CTYPE    =  f
 LATLON   = 0
 MAP      = 1/1/3
r

endgdcntr

gpend

mv gempak.gif 
'/home/dnovak/research/Ensembles/12Feb_2006/plots/12Feb_probprecip.gif'