Number Range Problem

I am uploading a file into ztable and i am creating a unique number attach to a file in Ztable using Number Range (SNRO).

I have created 2 work areas ...1 for file data and 1 for unique Number. I having problem uploading unique number to the corresponnding data in Ztable.

It showing me error that work area is not long enogh. How to deal with this? Attached is my copy of program file.