connection problems with java server and db2

Hi all I have a problem . I am trying to connect to db2 using a java server within the host and database its' in the vitual machine . It was working fine until yesterday , however now I got this error message :

SQL Exception: [jcc][t4][2043][11550][4.7.85] Exception java.net.ConnectExceptio
n: Error opening socket to server localhost/127.0.0.1 on port 50.000 with messag
e: Connection refused: connect. ERRORCODE=-4499, SQLSTATE=08001

I did verify if TCPIP is properly enabled in db2 using db2set -all ...and then redoing again the steps :

db2set DB2COMM=TCPIP
db2 update dbm cfg using SVCENAME 50000
db2stop
db2start

I am using db2 v10 ubuntu 12 on virtualbox , host windows 7 ..aplication server java is on host

but nothing . Still having this error popping up . If anyone could help or give me some suggestion of what I am doing wrong