[Zope-dev] Key error using manage_changeProperties

I am pssing the category argument to the method below. The category variable is representing a propety of the Log object. My code below works ok when I get the property (1), but fails when I try to update that property (2) with a new value. I have tried to use _[category] but it disallowes the use of expression, understandably, as a keyword. Any ideas how I can get around this problem? Cheers, Espen <dtml-let (1)value="_.getattr(userFolder,username).Log.getProperty(category)" newvalue="value+......."> (2)<dtml-call "_.getattr(userFolder,username).Log.manage_changeProperties(category=newvalue)"> </dtml-let>