It isn't unusual to not have avast detect on VT when it does so on your system. VT isn't able to update the VPS in real time as the user is and this is often the cause. Remember the point of submitting it to VT is to see what the other scanners find.
Send the sample to
virus@avast.com zipped and password protected with the password in email body, a link to this topic might help and false positive in the subject.
Or you can also add the file to the User Files (File, Add) section of the avast chest (if it isn't already there) where it can do no harm and send it from there (select the file, right click, email to Alwil Software). No need to zip and PW protect when the sample is sent from chest. A copy of the file/s will remain in the original location, so any further action you take can remove that.
If it is indeed a false positive and it seems so, see
http://forum.avast.com/index.php?topic=34950.msg293451#msg293451, how to report it to avast! and what to do to exclude them until the problem is corrected.
