FreeNX error : Error is 112 'Address already in use'

When I try to connect to Ubuntu from FreeNX client ( Windows ) , I have faced the following error.

error message on NX client

Info: Connection with remote proxy completed. Error: Call to bind failed for font TCP port 11001. Error is 112 'Address already in use'.

# apt-cache policy nxserver nxserver:  Installed: 3.5.0-11  Candidate: 3.5.0-11  Version table: *** 3.5.0-11 0        100 /var/lib/dpkg/status # apt-cache policy nxnode nxnode:  Installed: 3.5.0-9  Candidate: 3.5.0-9  Version table: *** 3.5.0-9 0        100 /var/lib/dpkg/status

I try to connect to two different Linux boxes from the same NX client at a time.
I can establish the first NX session , however I can’t establish the second NX session...

NX client (windows ) --- NX server ( Ubuntu 12.04 )  <- can establish :D
                    --- NX server ( Linux Mint 13 )  <- can’t establish :(

NX client seems to use the same TCP port number for both NX session.
To solve this , edit node.cfg on the NX server to avoid the NX client using same TCP port.

- on the Ubuntu 12.04 box ( NX server )

# egrep -i ^display /usr/NX/etc/node.cfg DISPLAY_BASE=1000 DISPLAY_BASE + 3000

restart NX server

# /etc/init.d/nxserver restart

- on the Linux Mint 13 box ( NX server )

# egrep -i ^display /usr/NX/etc/node.cfg DISPLAY_BASE=2000 DISPLAY_BASE + 4000

restart NX server

# /etc/init.d/nxserver restart

After editing node.cfg , I can connect to the two NX server boxes on the same NX client at a time.