The NEXTVAL(SEQUENCE, STARTVAL) function returns the next value in the specified sequence. The sequence is created if it does not exist and assumes a starting value of startval. If no startval is given, sequence always starts from 1.
Parameters: SEQUENCE: a sequence, STARTVAL: starting value
Return value: a string representing the next value in the SEQUENCE
Example: @nextval(EXAMPLE, 10)@, Result: 10 ( Each subsequent click of “Validate” increments by 1.)
If you want your sequence to increase by 1 from the starting value and increase for each row, have you tried CUSTOMLUHN(NUMBER,INDEX,LENGTH,[SEEDVALUE]), NEXTSTRINGVAL(SEQUENCE, STARTVAL, CHARS), or NEXTVAL(SEQUENCE) ?
If these do not help, I suggest reaching out to your CA Account Manager to find a resource to help you implement what you want in your environment.