Ensure that the system date is correct, day/month/year and adjust as required.
If it is correct - Have you tried a manual update from the avast UI, see image.
Try a repair of avast. Add Remove programs, select 'avast! Anti-Virus,' click the Change/Remove button and scroll down to Repair, click next and follow. This has in the past resolved this out of sync issue between reported and actual VPS version.