Norton Internet Security 2009 / NAV 2009 cannot detect Bagle !!!

I've been infected by bagle today, and I asked norton to analyse the computer, full scan, compressed files included

 

I did it in windows vista running, then in safe mode, then in safe mode by MSconfig as advised by Symantec ...

 

NAV never detected it ... and u know what's the most funny fact? My uptodate full security NIS2009 failed at detecting it BUT my 2 years old Bitdefender V.10 did and it's virus defs weren't even uptodate !!! ==> WTF Symantec? do you know that you asked me 89 euros for nothing?

 

I really would like to be given some explaination about this epic NAV fail ...

 

So, why didn't NAV detect bagle when old bitdefender did and solved my problem?

Are there other malwares that NIS don't protect us from?

 

Anyways, i hope my computer will work correctly again ...

 

My final question is : why did i get infected by a 4 years old version of bagle with NIS2009 full uptodate installed ?