How to fix this Logmein Hamachi Problem?

I have a vanilla Minecraft server me and my friends play on. We've always used a network I made on Logmein Hamachi to enable us to connect (I believe). Recently though one friend hasn't been able to access the server as on his hamachi I appear with a triangle next to my name with an explanation mark inside. On 'details' when he views me it says 'error' on VPN status and Status.

Please help me fix this issue.
Much appreciation for any answers,
Chris.

Well in this case i recommend you to use VPNMaster to unblock sites and surf anything. Their service is fast and much cheaper. I have been using their services since 2 years.
Here's the link. You can check this out.
http://www.vpnmaster.org