I read in another article to check the DB, Instance, and Session NLS_DATE_FORMAT parameter setting values. In DB1 and DB2 on our system each is the same "DD-MON-RR"/null/"DD-MON-RR" respectively; so from that point of view this shouldn't be the source of the problem.
I then read in another forum article to set the "NLS_DATE_FORMAT" key on my machine (i.e. "DD-MON-RR" in my case), however I don't have administrator privileges to create the key (we are not given admin privileges to the laptops we use) :
[HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\YOUR_ORA_HOME]
"NLS_DATE_FORMAT"="dd.mm.yyyy hh24:mi:ss"