Resuming suspended NX sessions; how?

Hello, I just started using NoMachine's NX technology for remote desktops. I installed FreeNX, NX and kNX as the frontend. I started a new session to my local system using kNX and then suspended it. However, after trying to reconnect several times I get no access to the saved (suspended) session; instead, a new session is created from scratch and I can see (as root) several sessions if I issue nxserver --list. How can I reconnect to a suspended session? Note that from a Windows machine, I tried the NoMachine Windows client. I could see the sessions there waiting to be resumed, but the resume button was disabled. Best regards, Carlos.