I'm trying to create a database query because I need some data from more database table so I would like to use join.
First I've tried with adding it manually to the collections. The sql expression is the simplest for just the sake of test - like 'select UID_TroubleTicket from TroubleTicket where isClosed = 0''. I tried it with adding the UID_TroubleTicket property to the collection also. Unfortunately the collection is always empty. Tried it with loading the data in the Initializer, but with that I got an error.
I've tried it with the wizard, it showed me the data in the window where I can test my query, but than when I open the page it shows error: