Why am I getting a divide-by-zero error?

["Owen Davies" <owen@xxxxxxxxxxxxx>]

I haven't paid much attention to the Chande Momentum Oscillator,
so when someone mentioned it here the other day, I decided to 
take a look at it.  In one "system" I made to study its behavior,
I tried to do a simple comparison: CMO(n) > CMO(n)[1].  For
no reason I can begin to understand, SC4 came up with a
divide-by-zero error.  Does anyone know what causes this,
and what can be done to get around it?

Many thanks.

Owen Davies