public shared function nulltodate(byval obj as object) as date
           dim isvalid as boolean = false
 
           if obj is nothing then isvalid = false
           if isdbnull(obj) = false then isvalid = false
           if isdate(obj) = false then isvalid = false
 
           if isvalid = false then
               return new date(now.tostring("yyyy/mm/dd"))
           else
               return convert.todatetime(obj)
           end if
       end function