Compositing wind and pressure data based on certain OLR values

[Jason Snyder]

I am trying to make a script that composites pressure values from dates
when OLR values over a certain area (latitude range: 15S to 15N and
longitude: 120E and 120W) are below a certain value.  I tried using this
script and it did not seem to work properly.  What should I do to make
this script so that I can make this script work properly?  Also how can I
composite wind data at specific pressure levels such as 850 mb and 500 mb
based on this script?
'sdfopen olr.day.mean.nc'
'sdfopen pres.sfc.1993.nc'
'set t 6790'
'define presa = 0'
count = 6790
while (count < 12267)
   'set t 'count
   'define olra = aave(olr,lon=120,lon=240,lat=-15,lat=15)'
   'd count'
   if (olra < 230)
      'define presb = pres.2'
   else
      'define presb = 0'
   endif
'define presa = presa + presb'
count = count + 1
endwhile
'define presavg=presa'

-Jason