Help bug in code

[henry218]

 {
       for(i = 0; i < limit; i++)
           Spread1[i] = (iClose(FirstMarket, 0, i-1) - iClose(FirstMarket, 0, i))/(iClose(FirstMarket, 0, i));
           
           
          
     }

Hello I am trying to additionne all the returns in an indicator but I have somme difficulties. I did the first part(computing the returns but I don't manage to add them). Anyone has an idea? 

[William Roeder]

When i is zero, iC(i-1) does not exist