string sel_claims = ds.Tables[0].Rows[0]["claims_description"].ToString();
int indx2 = drpClaimType.Items.IndexOf(drpClaimType.Items.FindByText(sel_claims));
drpClaimType.SelectedIndex = indx2;
set a break point on first line and check the value in the sel_claims variable, make sure this value is available in the drpClaimType.Items list. I think drpClaimType.Items.FindByText method is case sensitive.