Task: empty window when choosing responsible

Hi. We have installed e-groupware 1.4 and we are having a recursive problem with tasks. Whenever creating a task and choosing a responsible (third tab, pressing magnifier), an empty window pops up. It should bring other users and groups to be chosen, but it don't. I noticed that a similar window is open when creating a calendar item. The url for this window is below. Note that the parameter &app=calendar is present. http://groupware.tre-sc.gov.br/egroupware/index.php?sessionid=&domain=default&menuaction=phpgwapi.uiaccountsel.popup&app=calendar&use=both&element_id=eT_accountsel_exec_participants_account_&multiple=1 Below is the url when empty window appears when creating task responsible via magnifier. Note that parameter &app= is empty. http://groupware.tre-sc.gov.br/egroupware/index.php?sessionid=&domain=default&menuaction=phpgwapi.uiaccountsel.popup&app=&use=both&element_id=eT_accountsel_exec_info_responsible_&multiple=10 If I copy this url and fill the app parameter and refresh the window, it shows the correct content. Has anyone a tip, fix or any help? Thanks. Israel