I had the following error when i try the hetro noe. >>> Exception in Tkinter callback Traceback (most recent call last): File "/home/karthik/ccpnmr.new/ccpnmr/python2.4/lib/python2.4/lib-tk/Tkinter.py", line 1345, in __call__ return self.func(*args) File "/home/karthik/ccpnmr.new/ccpnmr/python2.4/lib/python2.4/lib-tk/Tkinter.py", line 456, in callit func(*args) File "/home/karthik/ccpnmr.new/ccpnmr/ccpnmr1.0/python/ccpnmr/analysis/CalcHeteroNoePopup.py", line 557, in update datum.append( float(intensA)/intensB ) TypeError: unsupported operand type(s) for /: 'float' and 'NoneType' Karthik