Virus not found by Avast

Avast Free Antivirus / Premium Security
1

I downloaded a file from p2p, and i read in the comments that it was a virus. In any case I downloaded it and I tried my avast home edition updated to 4.1.396 and 0423-3 (today). Avast did not find any virus. So I used TrendMicro online antivirus and it found BKDR.nucledor.a in the two files I downloaded (nwc.exe and nwc.dll).
Why avast did not recognize the viruses? Is it safe at all?

2

The file is not safe.You must send the samples to a emailadress from Avast.And Avast can’t reconize all virusses :frowning: but it is the best free-av

3
Avast can't reconize all virusses

I honestly don’t think there is an AV that does, with internet threats increasing everyday.