To test the validity of a zip archive using the Xceed Zip compression library, you should use the TestZipFile method as explained in the online documentation available at the page:
Find next an example code on how to implement in VB:
Dim ResultCode As xcdError
Call XceedZip1.License( "your license key" )
' Set the name and path of the zip file to test
XceedZip1.ZipFilename = "c:\test\zip.zip"
' Start testing the file (we use True here so that we also test the actual compressed data, not just the zip file's structure)
ResultCode = XceedZip1.TestZipFile(True)
' Check the return value
If ResultCode <> xerSuccess Then
MsgBox "Unsuccessful. Error #" & Str(ResultCode) & " occurred. " & "Description: " & _
MsgBox "The tested zip file is completely error-free."
Xceed - Software Developer and Technical Support