[Zope] parameter passing syntax

Thanks fo rthe support In my dtml document the DTML-IN tag used to fill the data in my 2nd combobox in my form i'm using a ZSQL method with one param districtname. this value i've to get from the submit of the same form upon selecting from 1st combobox 'districtname'. the dtml-in tag i used goes like this: <dtml-in getDistrictUser (districtname=REQUEST.form.districtname)> <dtml-var username> </dtml-in> error on saving changes: document template parse error, invalid attribute name getDistrictUser(districtname for tag "<dtml-in...." both the parameter name n the first combobox name is "districtname" . i made them similar thinking it wud take the request variable automatically. plz help me out sir.