Its possible create a key autonumber?

HI,

I wait that you can understandme because I only speak a little english.

I want to create a table with a key field that is autonumber. I create a range number object with SNRO but when I assign this range to the field and I add a register, the number it's no create. I use sm30 to add registers.

How can I create a key autonumber?

Thank you very mucho.