diff --git a/common/lib/capa/capa_problem.py b/common/lib/capa/capa_problem.py
index b14001ef03..a341f954bc 100644
--- a/common/lib/capa/capa_problem.py
+++ b/common/lib/capa/capa_problem.py
@@ -200,6 +200,7 @@ class LoncapaProblem(object):
         self.student_answers = answers
         oldcmap = self.correct_map				# old CorrectMap
         newcmap = CorrectMap()					# start new with empty CorrectMap
+        log.debug('Responders: %s' % self.responders)
         for responder in self.responders.values():
             results = responder.evaluate_answers(answers,oldcmap)      # call the responsetype instance to do the actual grading
             newcmap.update(results)
diff --git a/common/lib/capa/correctmap.py b/common/lib/capa/correctmap.py
index f694391cc6..ec3fed54c2 100644
--- a/common/lib/capa/correctmap.py
+++ b/common/lib/capa/correctmap.py
@@ -17,11 +17,17 @@ class CorrectMap(object):
 
     Behaves as a dict.
     '''
-    cmap = {}
-
     def __init__(self,*args,**kwargs):
+        self.cmap = dict()		# start with empty dict
+        self.__getitem__ = self.cmap.__getitem__
+        self.__iter__ = self.cmap.__iter__
+        self.items = self.cmap.items
+        self.keys = self.cmap.keys
         self.set(*args,**kwargs)
 
+    def __iter__(self):
+        return self.cmap.__iter__()
+
     def set(self, answer_id=None, correctness=None, npoints=None, msg='', hint='', hintmode=None):
         if answer_id is not None:
             self.cmap[answer_id] = {'correctness': correctness,
@@ -47,7 +53,7 @@ class CorrectMap(object):
         dict of dicts format.
         '''
         if correct_map and not (type(correct_map[correct_map.keys()[0]])==dict):
-            for k in self.cmap.keys(): self.cmap.pop(k)				# empty current dict
+            self.__init__()							# empty current dict
             for k in correct_map: self.set(k,correct_map[k])			# create new dict entries
         else:
             self.cmap = correct_map
@@ -98,9 +104,5 @@ class CorrectMap(object):
             raise Exception('CorrectMap.update called with invalid argument %s' % other_cmap)
         self.cmap.update(other_cmap.get_dict())
 
-    __getitem__ = cmap.__getitem__
-    __iter__ = cmap.__iter__
-    items = cmap.items
-    keys = cmap.keys
 
     
diff --git a/common/lib/capa/responsetypes.py b/common/lib/capa/responsetypes.py
index 5a5296d805..a63cb991cf 100644
--- a/common/lib/capa/responsetypes.py
+++ b/common/lib/capa/responsetypes.py
@@ -158,6 +158,7 @@ class LoncapaResponse(object):
         '''
         new_cmap = self.get_score(student_answers)
         self.get_hints(student_answers, new_cmap, old_cmap)
+        # log.debug('new_cmap = %s' % new_cmap)
         return new_cmap
 
     def get_hints(self, student_answers, new_cmap, old_cmap):
@@ -492,7 +493,7 @@ def sympy_check2():
                 if cfn in self.context:
                     self.code = self.context[cfn]
                 else:
-                    msg = "%s: can't find cfn in context = %s" % (unicode(self),self.context)
+                    msg = "%s: can't find cfn %s in context" % (unicode(self),cfn)
                     msg += "\nSee XML source line %s" % getattr(self.xml,'sourceline','<unavailable>')
                     raise LoncapaProblemError(msg)
 
@@ -896,7 +897,7 @@ class FormulaResponse(LoncapaResponse):
                                            given, 
                                            cs = self.case_sensitive)
             except UndefinedVariable as uv:
-                log.debbug('formularesponse: undefined variable in given=%s' % given)
+                log.debug('formularesponse: undefined variable in given=%s' % given)
                 raise StudentInputError(uv.message+" not permitted in answer")
             except Exception, err:
                 #traceback.print_exc()