File Selection Widget for file on Knime BUsiness hub

Dear KNIME Community
I want to have a widget with which the user can select a file from several ones which are located on the KBH.
Trying this with the File Chooser WIdget I can select a file, but when i forward it to an excel reader the error is:
Execute failed: The specified file knime:/knime-business-hub/FILE does not exist.

any idea how this could be handled?