Document numbering ... non superusers cant use documents.

I have all document numbers linked to financial periods. However, for each of the series defined, group reads as '1'.

Now, any non-superuser cannot create transactions , as the system alerts 'document numbering' has to be defined first.

As a quick solution, ive had to define these users as superusers , and they can key transactions.

But how do I resolve this issue ? What is the meaning of the 'GROUP' field in document numbering definition. I noticed, that group reads as '-1' for non-superusers.

Please help.