diff --git a/CMakeLists.txt b/CMakeLists.txt
index cfab179c..43ec1499 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -21,7 +21,7 @@ include(CTest)
 set(OSTAP_VERSION_MAJOR 1)
 set(OSTAP_VERSION_MINOR 9)
 set(OSTAP_VERSION_PATCH 2)
-set(OSTAP_VERSION_TWEAK 3)
+set(OSTAP_VERSION_TWEAK 4)
 
 set(OSTAP_VERSION ${OSTAP_VERSION_MAJOR}.${OSTAP_VERSION_MINOR}.${OSTAP_VERSION_PATCH}.${OSTAP_VERSION_TWEAK})
 
diff --git a/ReleaseNotes/release_notes.md b/ReleaseNotes/release_notes.md
index 5d2e553d..e5dae6ca 100644
--- a/ReleaseNotes/release_notes.md
+++ b/ReleaseNotes/release_notes.md
@@ -1,9 +1,13 @@
+# v1.9.2.4
+
 ## New features: 
 
 ## Backward incompatible:  
 
 ## Bug fixes:
 
+ 1. fix newly introduced typo in drawing for simulltaneous pdf. Thanks to Dima Pereima for reporitng a problem! 
+
 # v1.9.2.2
 
 ## New features: 
diff --git a/ReleaseNotes/v1.9.2.4.md b/ReleaseNotes/v1.9.2.4.md
new file mode 100644
index 00000000..8bfa3e7c
--- /dev/null
+++ b/ReleaseNotes/v1.9.2.4.md
@@ -0,0 +1,9 @@
+# v1.9.2.4
+
+## New features: 
+
+## Backward incompatible:  
+
+## Bug fixes:
+
+ 1. fix newly introduced typo in drawing for simulltaneous pdf. Thanks to Dima Pereima for reporitng a problem! 
diff --git a/ostap/fitting/simfit.py b/ostap/fitting/simfit.py
index c45f1acd..3a7723b8 100644
--- a/ostap/fitting/simfit.py
+++ b/ostap/fitting/simfit.py
@@ -590,8 +590,6 @@ def __init__ ( self              ,
                'Invalid type for "sample":' % ( sample ,  type ( sample ) )
         
         name = name if name else self.generate_name ( 'simfit' , '' , sample.GetName() )
-
-
         
         ## propagate the name 
         self.name = name
@@ -837,6 +835,7 @@ def draw ( self           ,
         >>> pdf.fitTo ( dataset )
         >>> pf.draw ( 'signal' , dataset , nbins = 100 ) 
         """
+
         dvar = None
         if   isinstance ( category , ( tuple , list ) ) and 2 == len ( category ) :
             category , dvar = category 
@@ -913,7 +912,7 @@ def draw ( self           ,
                     return None
                 
             elif isinstance ( draw_pdf , PDF2 ) :
-
+                
                 if   2 == dvar or dvar in  ( 'y' , 'Y' , '2' , draw_pdf.yvar.name ) :
                     return draw_pdf.draw2 ( dataset = dataset ,
                                             nbins   = nbins   ,
@@ -928,12 +927,14 @@ def draw ( self           ,
                     self.error("Unknown 'dvar' for 2D-draw pdf! %s" %  dvar )
                     return None 
 
-            elif isinstance ( draw_pdf , PDF3 ) :
-                
+            elif isinstance ( draw_pdf , PDF1 ) :                
                 return draw_pdf.draw ( dataset = dataset ,
                                        nbins   = nbins   ,
                                        silent  = silent  ,
                                        args    = args    , **kwargs )
+
+            self.error ("draw: inconsistent combination of draw_pdf '%s' and dvar '%s'" % (
+                type ( draw_pdf ) , dvar ) )
             
     # =========================================================================
     ## create NLL
diff --git a/ostap/fitting/tests/test_fitting_simfit1.py b/ostap/fitting/tests/test_fitting_simfit1.py
index 65b8ed80..6735bad8 100755
--- a/ostap/fitting/tests/test_fitting_simfit1.py
+++ b/ostap/fitting/tests/test_fitting_simfit1.py
@@ -114,14 +114,16 @@ def test_simfit1 () :
     model2.S = NS2
     model2.B = NB2 
     
-    with use_canvas ( 'test_simfit1' ) : 
+    with use_canvas ( 'test_simfit1: fit dataset1' ) : 
         # =========================================================================
         ## fit 1
         with wait ( 1 ) : 
             r1 , f1 = model1.fitTo ( dataset1 , draw = True , nbins = 50 , silent = True )
             title = 'Results of fit to dataset1'
             logger.info ( '%s\n%s' % ( title , r1.table ( title = title , prefix = '# ' ) ) )
+
         
+    with use_canvas ( 'test_simfit1: fit dataset2' ) : 
         ## fit 2
         with wait ( 1 ) : 
             r2 , f2 = model2.fitTo ( dataset2 , draw = True , nbins = 50 , silent = True )
@@ -150,11 +152,10 @@ def test_simfit1 () :
     title = 'Results of simultaneous fit'
     logger.info ( '%s\n%s' % ( title , r.table ( title = title , prefix = '# ' ) ) )
     
-    with use_canvas ( 'test_simfit1' ) :
-        with wait ( 1 ) : 
-            fA = model_sim.draw ( 'A' , dataset , nbins = 50 )
-        with wait ( 1 ) : 
-            fB = model_sim.draw ( 'B' , dataset , nbins = 50 )            
+    with wait ( 2 ) , use_canvas ( 'test_simfit1: fit both datasets & draw A' ) :        
+        fA = model_sim.draw ( 'A' , dataset , nbins = 50 )
+    with wait ( 2 ) , use_canvas ( 'test_simfit1: fit both datasets & draw B' ) :        
+        fB = model_sim.draw ( 'B' , dataset , nbins = 50 )            
 
     models.add ( model1        )
     models.add ( model2        )
@@ -196,13 +197,12 @@ def test_db() :
 if '__main__' == __name__ :
 
 
-    
     with timing( "simfit-1" ,   logger ) :  
-        test_simfit1 ()
+       test_simfit1 ()
         
     ## check finally that everything is serializeable:
     with timing ('Save to DB:'     , logger ) :
-        test_db ()          
+       test_db ()          
  
 # =============================================================================
 ##                                                                      The END