Private Sub txtCode_Change()
         ' whenever txtCode changes, set field value. 
         ' This is safer than using lost focus, as the field can
         ' change without getting focus 
 
         Dim iRet As Integer
 
         If txtCode <> "" Then
             iRet = LceSetFieldValueU(iSession, "TOWN", txtCode)       
         Else
             ' "" is not a null terminated string
             iRet = LceSetFieldValueU(iSession, "TOWN", vbNullString)
         End If
     End