Virsues not been cought by Symantec

Dears, i was working with Symantec customer he report to me that he has a virus in his network that are copy it self to each media usb attached and duplicated it's file. i guide him to extract that virus and send to me my machine is working under SEP 12.1.2 with the maximum security level ever. my machine couldn't detect that virus, i submit it to Symantec via essential virus report on last Wed and i submit it again on Sat until now SEP couldn't catch that virus and i begin to feel that my network is not save as well that customer and Symantec support team didn't give us the appropriate care. i upload the file to threatexpert and it report as below. +++++++++++++++++++++++++++++++++++++++++ Submission details: Submission received: 4 March 2013, 06:02:02 AM Processing time: 6 min 46 sec Submitted sample: File MD5: 0x2327B0E73D0A6D7BAC4E9D083D737455 Filesize: 308,266 bytes Alias & packer info: Trojan-Downloader.Win32.AutoIt.lq [Kaspersky Lab] W32/YahLover.worm.gen [McAfee] Mal/Sohana-A [Sophos] Worm.Autoit [Ikarus] packed with UPX [Kaspersky Lab] +++++++++++++++++++++++++++++++++++++++++++ i am not sure what to do right now i am not infected but if this infect my network then who well be blame for such thing. i can solve the problem in customer side by applying application control MD5 and delete the infection by using risk-disk from kaspersky but how can i be sure i that i am not gonna be infected again by such thing, i am totally hopeless.