[las_users] Problem with regridding hybrid-z data to a fixed-z grid

[Bernhard Giner <giner@xxxxxxxxxxxxxxxxx>]

Hi all,
I am trying to regrid hybrid_z to a fixed z grid as described here:
http://ferret.pmel.noaa.gov/LAS/documentation/installer-documentation/adding-data-with-hybrid-z-coordinates/configuring-las-to-regrid-hybrid-z-data-to-a-fixed-z-grid
I've got  4D atmosperical chemistry simulation data like O3 ordered in 90 
hybrid z-slices from space to ground, and I've got  another 4D Datafile in 
with the 90 pressure levels (Pa) at the same time-values.
Now I try to use this pressure-file to regrid my O3 Z-axe... 
I constantly get the following Error:
---
 **ERROR: command syntax: invalid nested brackets: GZ=PRESS[D= ]
DEFINE VARIABLE kmax = `z[gz=press[d= ]],return=size`
Command file, command group, or REPEAT execution aborted
STOP -script mode, ERROR RUNNING SCRIPT statement executed
---
The last Ferret command was:
LET kmax = `z[gz=($ferret_thk_var)[d=($thk_num)]],return=size`

it seems that there is a problem with $thk_num,
It doesn't change anything if I select Native Z Coordinates = yes or no in the 
constraint menu
Any idea where I am wrong?
(LAS Armstrong 1.1.1, ferret V6.1)

Regards 
Bernhard Giner
-- 
Max Planck Institute for Chemistry
Department of Atmospheric Chemistry
Joh.-Joachim-Becher-Weg 27, D-55128 Mainz 
P.O. Box 3060, 55020 Mainz, Germany
Phone: (+49 6131) 305 - 449
Fax: (+49) (0)6131 305 - 436