Hi Sofie,
Looks like idocs are not transferred to BW from ECC (source system).
In the infopacakge monitor screen-->environment -->transact RFC-->in source system-->enter you source system credentials-->then choose the appropriate date (Display period) on when this hierarchy error-ed out.
if you see any idocs.. execute them (F6), once idocs are cleared, come back to infopackage and refresh the monitor.