autonumber column - datagridview

Question

hello :) i have a datagridview populated from a bindingsource and i've tried in many ways to add an autonumber column. I've found some solutions on the Internet, but still doesn't work.:( here's my code:

SqlDataAdapter dataAdapter2 = new SqlDataAdapter("SELECT * FROM categorie_discount_adaos", conn);

dataAdapter2.Fill(dataSet, "categorie_discount_adaos");

 categdaGridView.AutoGenerateColumns = false;

 categdaBS.DataSource = dataSet.Tables["categorie_discount_adaos"];

categdaGridView.DataSource = categdaBS;

categdaGridView.Columns["denumire_categorie"].DataPropertyName = "denumire_categorie";

categdaGridView.Columns["tip_categorie"].DataPropertyName = "tip_categorie";

 categdaGridView.Columns["procent"].DataPropertyName = "procent";

//i've tried this

int cellnum = 0;

            int rownum = 0;

            foreach (DataGridViewRow row in categdaGridView.Rows)

            {

                cellnum = cellnum + 1;

                categdaGridView.Rows[rownum].Cells[0].Value = cellnum;

                rownum = rownum + 1;

            }