Label compname = (Label)DetailsView1.Rows[1].Celles[0].FindControl("complbl");
that is the right syntax, but the error is pointing to a different source. Try doing this one:
if(DetailsView1.Rows.Count != 0)
{
Label compname = (Label)DetailsView1.Rows[1].Celles[0].FindControl("complbl");
}
Regards,
Eduard