Checkbox value is not retained on postback

I have a webform that have mutiple collectins of check boxes created on run time ( database driven),
i create id's and add it to an array .
later while updating i find control the id's and check if it is checked.
Though teh checkbox is unchecked it takes its old value as checked is true, please help to solve.
below is teh code which i am calling on submit .
 
private void GetValuesAndUpdate(int intRowId)
    {
        CheckBox chkBox;
        string strRoleOk;
        string strActiveFlag;
        if (Session["CheckBoxIDs"] != null && Session["CheckBoxIDs"].ToString() != String.Empty)
        {
            ArrayList alCh ...