the error is likely being thrown on the first record which, by design, has no previous record
try adding another line of code at the begining of your formula . . .
if onfirstrecord then "" else . . . . .
the error is likely being thrown on the first record which, by design, has no previous record
try adding another line of code at the begining of your formula . . .
if onfirstrecord then "" else . . . . .