loop through gridview and check for one checkbox....

I need to loop through the Gridview to check for at least one checkbox and someone help me fix my codes.
 private bool Validate()         {             bool isValid = true;             int count = 0;             foreach (GridViewRow row in this.gvItemColor.Rows)             {                                 CheckBox ckboxDel = (CheckBox)row.FindControl("ckboxDel");                 if ((ckboxDel.Checked == true))        ...