V$SESSION not identifying program ...

Have two DBs with a link. When I quiz v$session for DB#2 it shows the users connected direct to DB#2 and the executables they are running. It also shows the DB link user account connections from DB#1. It shows what executables the users are running to access DB#1 - except 1 developer who says he is running TOAD.

If he connects direct to DB#2 with TOAD I see toad.exe as the executable in his v$session info for DB#2.

If he connects to DB#1 (which in turn uses a DBlink to DB#2)I can see his session in DB#2 but the program value is null.

If other users connect to DB#1 (which in turn uses a DBlink to DB#2)I can see their executable .exe names in the program value.

Anyone else experienced this? It means I can't be sure what tool the developer is using to connect to my DBs. (And yes, it might be important as I'm planning to use a LOGON system event to monitor who does what and when).