How to use counterField in the form Datasource?

Hi Experts,

I have tired using CouterField in the Form Datasource for a field which is real (EDT as LineNum at table level and it is the index for the table). But, I am getting Values like

1.00000

-1.00000

-2.00000

-3.00000

and so on for the new records.

Can anyone please tell where I am going wrong.

Thanks in advance.