Unable to cast the object of Type 'System.collections.generic.Keyvaluepair'[string,string] into type of 'System.IConvertible'

private void LoadUniversity()
{
    try
    {
        ObjUtility = new Utility();
        
        cmbUniversity.DataSource = ObjUtility.BindUniversity(StaticInfo.Center_Code).ToList();
          /* error is after this line (May be in BindUniversity method ) */
        
        cmbUniversity.DisplayMember = "Value";
        cmbUniversity.ValueMember = "Key";
        cmbUniversity.SelectedIndex = -1;
        cmbUniversity.Text = "--Select University--";
        ObjUtility = null;
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

public Dictionary<string, string> BindUniversity(string CenterCode)
{
    ObjUniversityInfoModel = new UniversityInfoModel();
    ObjUniversityInfoModel.CenterCode = CenterCode;
    ObjUniversityInfoServiceClient = new UniversityInfoServiceClient();
    ObjUniversityInfoModelRecordList = new List<UniversityInfoModel>();
    ObjUniversityInfoModelRecordList = ObjUniversityInfoServiceClient.GetUniversityInfoRecordList(ObjUniversityInfoModel);

    if (ObjUniversityInfoModelRecordList[0].Message == "Success" 
            && ObjUniversityInfoModelRecordList[0].Status == true)
    {
        var Result = from s in ObjUniversityInfoModelRecordList
        orderby s.UniversityID descending
        select new
        {
            s.UniversityID,
            s.UniversityName
        };
        ObjDictionary = new Dictionary<string, string>();
        foreach (var Item in Result)
        {
            string U_ID = Item.UniversityID.ToString();
            string U_Name = Item.UniversityName.ToString();
            ObjDictionary.Add(U_ID, U_Name);
        }
    }
    return ObjDictionary;
}