Using ObjectDataSource to populate a DropDownField

I am attempting to use an ObjectDataSource to populate a DropDownList. I am passing parameters to the following method in order to determine what should be in the drop down. I have determined that when a dataset is being referenced, the following error comes up: 

Error: There was an error rendering the control. Exception has been thrown by the target of an invocation. 

Code:

    public static DataView TstGetPhaseListForProjects(int projectId, int tableOrigin)
    {
      DataTable dt = new DataTable("PhaseList");
      dt.Columns.Add("code");
      dt.Columns.Add("name");

      string phaseNumber;

      DataSet dsData = new DataSet();
        //SqlHelper.ExecuteDataset(System.Configuration.ConfigurationManager.AppSettings[ODSComponentsLibrary.GlobalVars.CfgKeyConnStringODSNOP], SP_SELECT,
        //              tableOrigin, 0, projectId, "All");
      foreach (DataRow row in dsData.Tables[0].Rows)
      {
        phaseNumber = row["phase_no"].ToString();
        dt.Rows.Add(phaseNumber, phaseNumber);
      }


      return (dt.DefaultView);
    }



The above error shows up on the GridView rendering and the Gridview does not draw properly. 

Thanks in advance for your help.