As the error suggests you may be trying to update a field but no record is available.
You should check that a record is available before trying to manipulate the data.
eg.
the following statement may or may not find a record:
Code:
find first customer where customer.name begins "a" no-error.
So you check that the record is available before trying to do anything with it...
Code:
find first customer where customer.name begins "a" no-error.
If available customer then
do:
/* Insert code to manipulate the data here */
end.
If that's doesn't answer you question then please post your code so we can have a look.
HTH