why virus can't be detected

stageA

we use NOD32, if there is real time protection, why every time i scan manually, there are many virus to show up?

ESET Ben

Because "real time protection" is meaning if the file scan as virus is not causing any hazard, we will not delete it.
They will show up after scan, it will because the virus database is updated.
Therefore, frequently update the virus database is important.