If BP can't find an element at run time it's because the element as modelled at design time is not there. This will either be because the selection of attributes chosen by the developer is not unique or flexible enough to match the element in all situations, or because the synchronisation between the page logic and the application state is not being controlled. In other words, the logic is running too fast and the element is not yet present at the time when the business object tries to use it.