diff --git a/Code/Mantid/scripts/Inelastic/Direct/PropertiesDescriptors.py b/Code/Mantid/scripts/Inelastic/Direct/PropertiesDescriptors.py
index f07d804191bd..704112e19ae8 100644
--- a/Code/Mantid/scripts/Inelastic/Direct/PropertiesDescriptors.py
+++ b/Code/Mantid/scripts/Inelastic/Direct/PropertiesDescriptors.py
@@ -81,6 +81,8 @@ def __set__(self,instance,values):
               nBlocks = len(value);
           if nBlocks%3 != 0:
                raise KeyError("Energy_bin value has to be either list of n-blocks of 3 number each or string representation of this list with numbers separated by commas")
+       else:
+          value = None              
        #TODO: implement single value settings according to rebin
        object.__setattr__(instance,'_energy_bins',value);
 #end EnergyBins
diff --git a/Code/Mantid/scripts/test/DirectPropertyManagerTest.py b/Code/Mantid/scripts/test/DirectPropertyManagerTest.py
index 6c3bd72e1391..87f3bcc783de 100644
--- a/Code/Mantid/scripts/test/DirectPropertyManagerTest.py
+++ b/Code/Mantid/scripts/test/DirectPropertyManagerTest.py
@@ -1,9 +1,10 @@
+import os
+os.environ["PATH"] = r"c:/Mantid/Code/builds/br_master/bin/Release"
 from mantid.simpleapi import *
 from mantid import api
 import unittest
 import inspect
 import numpy as np
-import os
 import sys
 from Direct.PropertyManager import PropertyManager
 
@@ -435,6 +436,8 @@ def test_set_energy_bins_and_ei(self):
             self.assertAlmostEqual(en,ei[ind])
 
 
+        prop_man.energy_bins = None
+
         #TODO: this one is not completed
 
     def test_set_defailts_from_instrument(self) :
@@ -686,7 +689,7 @@ def test_hadmask_options_locked(self):
         self.assertFalse(propman1.use_hard_mask_only)
         self.assertEqual(propman1.hard_mask_file,'a_hard_mask_file.msk')
         self.assertTrue(propman1.run_diagnostics)
-
+