diff --git a/aprendizations/learnapp.py b/aprendizations/learnapp.py
index 8162b3a..d3abc98 100644
--- a/aprendizations/learnapp.py
+++ b/aprendizations/learnapp.py
@@ -44,8 +44,8 @@ class LearnApp(object):
             yield session
             session.commit()
         except Exception:
-            session.rollback()
             logger.error('DB rollback!!!')
+            session.rollback()
         finally:
             session.close()
 
diff --git a/aprendizations/questions.py b/aprendizations/questions.py
index 65c7635..8ac5bec 100644
--- a/aprendizations/questions.py
+++ b/aprendizations/questions.py
@@ -50,8 +50,6 @@ class Question(dict):
 
     async def correct_async(self) -> None:
         self.correct()
-        # loop = asyncio.get_running_loop()
-        # await loop.run_in_executor(None, self.correct)
 
     def set_defaults(self, d: QDict) -> None:
         'Add k:v pairs from default dict d for nonexistent keys'
@@ -94,7 +92,9 @@ class QuestionRadio(Question):
                                for x in range(n)]
 
         if len(self['correct']) != n:
-            msg = f'Options and correct mismatch in "{self["ref"]}"'
+            msg = (f'Options and correct mismatch in '
+                   f'"{self["ref"]}", file "{self["filename"]}".')
+            logger.error(msg)
             raise QuestionException(msg)
 
         if self['shuffle']:
@@ -168,18 +168,20 @@ class QuestionCheckbox(Question):
             }))
 
         if len(self['correct']) != n:
-            msg = f'Options and correct mismatch in "{self["ref"]}"'
+            msg = (f'Options and correct size mismatch in '
+                   f'"{self["ref"]}", file "{self["filename"]}".')
+            logger.error(msg)
             raise QuestionException(msg)
 
         # if an option is a list of (right, wrong), pick one
-        # FIXME it's possible that all options are chosen wrong
         options = []
         correct = []
         for o, c in zip(self['options'], self['correct']):
             if isinstance(o, list):
                 r = random.randint(0, 1)
                 o = o[r]
-                c = c if r == 0 else -c
+                if r == 1:
+                    c = -c
             options.append(str(o))
             correct.append(float(c))
 
@@ -187,8 +189,11 @@ class QuestionCheckbox(Question):
         # and apply to `options` and `correct`
         if self['shuffle']:
             perm = random.sample(range(n), k=self['choose'])
-            self['options'] = [str(options[i]) for i in perm]
-            self['correct'] = [float(correct[i]) for i in perm]
+            self['options'] = [options[i] for i in perm]
+            self['correct'] = [correct[i] for i in perm]
+        else:
+            self['options'] = options[:self['choose']]
+            self['correct'] = correct[:self['choose']]
 
     # ------------------------------------------------------------------------
     # can return negative values for wrong answers
@@ -443,20 +448,20 @@ class QFactory(object):
         'textarea':         QuestionTextArea,
         # -- informative panels --
         'information':      QuestionInformation,
+        'success':          QuestionInformation,
         'warning':          QuestionInformation,
         'alert':            QuestionInformation,
-        'success':          QuestionInformation,
         }
 
-    def __init__(self, question_dict: QDict = QDict({})) -> None:
-        self.question = question_dict
+    def __init__(self, qdict: QDict = QDict({})) -> None:
+        self.question = qdict
 
     # -----------------------------------------------------------------------
     # Given a ref returns an instance of a descendent of Question(),
     # i.e. a question object (radio, checkbox, ...).
     # -----------------------------------------------------------------------
     def generate(self) -> Question:
-        logger.debug(f'[generate] "{self.question["ref"]}"...')
+        logger.debug(f'[QFactory.generate] "{self.question["ref"]}"...')
         # Shallow copy so that script generated questions will not replace
         # the original generators
         q = self.question.copy()
@@ -487,7 +492,7 @@ class QFactory(object):
 
     # -----------------------------------------------------------------------
     async def generate_async(self) -> Question:
-        logger.debug(f'[generate_async] "{self.question["ref"]}"...')
+        logger.debug(f'[QFactory.generate_async] "{self.question["ref"]}"...')
         # Shallow copy so that script generated questions will not replace
         # the original generators
         q = self.question.copy()
diff --git a/aprendizations/tools.py b/aprendizations/tools.py
index a4f7e5c..be62ab3 100644
--- a/aprendizations/tools.py
+++ b/aprendizations/tools.py
@@ -145,7 +145,7 @@ def load_yaml(filename: str, default: Any = None) -> Any:
         logger.error(f'Cannot open "{filename}": not found')
     except PermissionError:
         logger.error(f'Cannot open "{filename}": no permission')
-    except IOError:
+    except OSError:
         logger.error(f'Cannot open file "{filename}"')
     else:
         with f:
--
libgit2 0.21.2