Crystal has a rigid cycle of doing things, which stops you re-using certain types of field.
Go back to the original field you summarised and do a grand total. If you've got Crystal 8.5, you ought to be offered this as an option when you right-click and choose [Insert] and [Summary]. It helps to put your version when asking a question, because different versions have different abilities.
Also look at running totals, which are subtler and have extra options.
Finally, upper case is conventionally understood as SHOUTING. Please don't unless you have something to shout about.
Madawc Williams (East Anglia)