[basex-talk] querying database

Hi,i have created a database in BaseX GUI but i did not understand how to use it inside FLWR query.So  since i would like to create one FLWR query to query all my files in the database not only one file with doc()i have tried collection()  is that right? (i have putted all my xml files inside path/ directory)This is my query: let $d:=collection ("path/")

let $r:=doc("myfile1.xml")

for $d in$d// item/@qcode="tx"

where $d//subj[text() contains text { 'Hal', 'Fade' } any] and$r/subj ="Berlin

"return

<results>$d/tit</results>

it shows me error: [XPTY0019] descendant::subj: node expected, xs:boolean found: false(). what is that error about?----Thank youBest regards