GeneXus - ejecutar store procedure

hola señores del foro estoy tratando de ejecutar un procedimiento almacenado en mi bd postgres desde mi aplicacion en genexus 8.0 win, y me genera el siguiente error cuando se intenta ejecutar: (Nota: lo ejecuto con el comando call y ya lo agregue en las propiedades del modelo), si me pueden colaborar gracias es urgente chao...

org.postgresql.util.PSQLException: This Statement [] defines a procedure call (needs ?= call <stmt> to be considered a function.
at org/postgresql/jdbc1/AbstractJdbc1Statement.registerOutParameter (AbstractJdbc1Statement.java:1778)
at com/genexus/db/driver/GXCallableStatement.registerOutParameter
at uprueba__default.setParameters (uprueba.java)
at com/genexus/db/DataStoreProvider.execute
at uprueba.E12V012 (uprueba.java)
at uprueba.actionEventDispatch (uprueba.java)
at com/genexus/ui/GXWorkpanel$runEvent.run
at com/genexus/uifactory/wfc/WFCUIFactory.invokeLater (WFCUIFactory.java)
at com/genexus/uifactory/UIFactory.invokeLater
at com/genexus/ui/GXWorkpanel.buttonActionPerformed
at com/genexus/ui/FocusManager.setFocusMouseClicked
at com/genexus/ui/FocusManager.mouseClicked
at com/genexus/uifactory/wfc/WFCMouseListener.mouseClicked (WFCMouseListener.java)
at com/ms/wfc/core/EventHandler.invoke (EventHandler.java)
at com/ms/wfc/core/Component.fireEvent (Component.java)
at com/ms/wfc/ui/Control.onClick (Control.java)
at com/ms/wfc/ui/Button.onClick (Button.java)
at com/ms/wfc/ui/Button.wndProc (Button.java)
at com/ms/wfc/ui/Control$ControlWindow.wndProc (Control.java)
at com/ms/wfc/app/Window.callback (Window.java)
at com/ms/wfc/win32/Windows.SendMessage (Windows.java)
at com/ms/wfc/ui/Control.sendMessage (Control.java)
at com/ms/wfc/ui/Control.reflectMessage (Control.java)
at com/ms/wfc/ui/Control.wmCommand (Control.java)
at com/ms/wfc/ui/Control.wndProc (Control.java)
at com/genexus/uifactory/wfc/ScrollPanel.wndProc (ScrollPanel.java)
at com/ms/wfc/ui/Control$ControlWindow.wndProc (Control.java)
at com/ms/wfc/app/Window.callback (Window.java)
at com/ms/wfc/win32/Windows.CallWindowProc (Windows.java)
at com/ms/wfc/app/Window.defWndProc (Window.java)
at com/ms/wfc/ui/Control$ControlWindow.defWndProc (Control.java)
at com/ms/wfc/ui/Control.defWndProc (Control.java)
at com/ms/wfc/ui/Control.wmMouseUp (Control.java)
at com/ms/wfc/ui/Control.wndProc (Control.java)
at com/ms/wfc/ui/Button.wndProc (Button.java)
at com/ms/wfc/ui/Control$ControlWindow.wndProc (Control.java)
at com/ms/wfc/app/Window.callback (Window.java)
at com/ms/wfc/win32/Windows.DispatchMessage (Windows.java)
at com/ms/wfc/app/Application$ThreadContext.runMessageLoop (Application.java)
at com/ms/wfc/app/Application.run (Application.java)
at com/ms/wfc/app/Application.run (Application.java)
at com/genexus/uifactory/wfc/WFCUIFactory.loopEvents (WFCUIFactory.java)
at com/genexus/uifactory/UIFactory.loopEvents
at com/genexus/ui/GXWorkpanel.run
at com/genexus/ui/GXWorkpanel.start
at uprueba.execute_int (uprueba.java)
at uprueba.execute (uprueba.java)
at uprueba.executeCmdLine (uprueba.java)
at uprueba.main (uprueba.java)