a simple trigger (gnue-forms)

Hello, 

Since in this period I don't have many 
things to do at work, I have some spare
time.  And i'll use some of this spare time
for gnue.  

I'm trying to create a trigger 
that copies the value of a certain 
field  (fldPu - the 'price')  into 
another field (fldVal - the 'value').

This one works:
<trigger name="Trigger1" type="POST-CHANGE"><![CDATA[##
v = blkProd.fldPu
print v
blkProd.fdlVal = 15
]]></trigger> 

But when I try this:
blkProd.fdlVal = v
or 
blkProd.fdlVal = float(v)

it says: 

Runtime Error occured:
 Traceback (most recent call last):
  File "<unknown_executioncontext>", line 12, in blkProd_fldPu_POST_CHANGE_Trigger1
  File "/usr/local/gnue/lib/python/gnue/common/logic/NamespaceCore.py", line 210, in __getattr__
    raise AttributeError, '%s' % (name)
AttributeError: __float__


I have tried various things, with no success.
(  blkProd.fldVal.setValue(15) and 
blkProd.fldVal.triggerSetValue(15) don't
work, too   ).


Does anyone know which is the correct method
for copying the value from one field to 
another ? 


Thank you,
Adrian Maier