I bought minecraft about 2 months ago, and despite my best efforts using hamachi and minecraft server software, I cannot get it working properly. I can get my friends to join my existing hamachi, and I can get the server up, and I can join it, but my friends cannot join it. My server properties file has the correct ip adress, and online mode IS set to false (Which as I have learned is the correct setting unless someone else can prove differently) andI even tried to match my friends setting in terms of what options are enables and which are not... however, I cannot seem to get it to work... Any ideas guys?

Do you have the latest server?

You need to download a new server file everytime Minecraft updates.