Snapshot doesn't start

I can't get the snapshot to work: Client> Exception in thread "main" joptsimple.MissingRequiredOptionException: Missing required option(s) ['version']
Client> at joptsimple.OptionParser.ensureRequiredOptions(OptionParser.java:447)
Client> at joptsimple.OptionParser.parse(OptionParser.java:437)
Client> at net.minecraft.client.main.Main.main(SourceFile:40)