Error in formula field of crystal reports when no records found

Question

I am working on crystal reports. I want to show the sum of the record on footer of every page. so I have added the formula field in crystal reports which have below formula.

whileprintingrecords;
numbervar PageTotl;

if isNULL({Customer.PaidAmount})Then 
0
else
PageTotl:=PageTotl + {Customer.PaidAmount}

its gives error below when there are no records present with given criteria.

What kind of changes I have to made in above code, so it can also handle the 0 records.

Answer 1

First, I got the same error, After fixing the formula to the following one, no errors came out:

whileprintingrecords;
numbervar PageTotl;

if isNULL({Customer.PaidAmount})Then 
0
else
PageTotl:=PageTotl + ToNumber({Customer.PaidAmount})