Objects not getting added to arraylist object

Hi,

This is my method:
 public ClsDMLProperties Add(string Column_Name, string Column_Value)
  {
  mCol = new ArrayList();
  ClsDMLProperties returnvalue;
  ClsDMLProperties ObjMember = new ClsDMLProperties();
  ObjMember.Col_Name = Column_Name;
  ObjMember.Col_Value = Column_Value;
  try
  {
  mCol.Add(ObjMember);
  }
  catch (Exception ex)
  {
  string msg = ex.Message;
  Console.WriteLine(msg);
  //DBCONObj.gprocErrorHandler(ex.Source, ex.Message, "Add", "ClsDMLFun");
  }
  returnvalue = ObjMember;
  ObjMember = null;
  return returnvalue;
  }
==========================
ClsDMLProperties Class
  public class ClsDMLProperties
  {
  private string column_name;
  private string column_value;
  private bool mvarReplaceBlankWithNull;
  private bool mvarAllowNull;
  private int mvarField_Decimals;
  private bool mvarisNumeric;


  public string Col_Name
  {
  get { return column_name; }
  set { column_name = value; }
  }
  public string Col_Value
  {
  get { return column_value; }
  set { column_value = value; }
  }
  public bool ReplaceBlankWithNull
  {
  get { return mvarReplaceBlankWithNull; }
  set { mvarReplaceBlankWithNull = value; }
  }
  public bool AllowNull
  {
  get { return mvarAllowNull; }
  set { mvarAllowNull = value; }
  }
  public int Field_Decimal
  {
  get
  { return mvarField_Decimals; }
  set
  { mvarField_Decimals = value; }
  }
  public bool IsNumeric
  {
  get
  { return mvarisNumeric; }
  set
  { mvarisNumeric = value; }
  }
  }
======================
My problem here is that to that arraylist object what i am adding does not get incremented. What could be the problem?