Index: openacs-4/packages/assessment/tcl/as-qti-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/assessment/tcl/as-qti-procs.tcl,v
diff -u -r1.50 -r1.51
--- openacs-4/packages/assessment/tcl/as-qti-procs.tcl	7 Aug 2017 23:48:03 -0000	1.50
+++ openacs-4/packages/assessment/tcl/as-qti-procs.tcl	12 Feb 2019 17:12:18 -0000	1.51
@@ -849,14 +849,14 @@
                     set selected_p f
                     set as_item_choices__ident [$response_label getAttribute {ident}]
                     set mattextNodes [$response_label selectNodes {material/mattext}]
-                    set as_item_choices__choice_text [db_null]
+                    set as_item_choices__choice_text ""
                     # get the title of each choice
                     foreach mattext $mattextNodes {
                         set as_item_choices__choice_text [as::qti::mattext_gethtml $mattext]
                     }
                     # for multimedia items
                     set matmediaNodes [$response_label selectNodes {material/matimage[@uri]}]
-                    set as_item_choices__content_value [db_null]
+                    set as_item_choices__content_value ""
                     foreach matmedia $matmediaNodes {
                         set mediabasepath [file join $basepath [$matmedia getAttribute {uri}]]
                         # insert as_file in the CR (and in the as_file table) getting the content value