Michelle, 
Cecil and David's code was correct but could not match Ken's spreadsheet
output due to a slight mis-specification in Ken's Excel spreadsheet. The code
was then modified to conform with Ken's specification and results very close
to that of Ken were obtained. As of now Ken's modifying his spreadsheet to
re-run the results, the original correct code will be restored, and we will 
see what
happens then. Anyway this is rather encouraging. 

Best,
Alex