I installed Vantage Synchrony PassPort V3.4.4 on Vantage V1.3.6 on Linux. Out of the box, I receive an exception when I connect to the synchrony-vantage portal and attempt to administer Vantage.
The PassPort tab says:
"Error      
An error occured while processing your request
If the problem persists, please contact the administrator."

The exception on the PassPort Administration tab reads:
"An error occured while rendering the portal
java.lang.NoClassDefFoundError
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:274)"

The problem may be that libXp.so.6 is missing. This library was used by Java 1.4''s AWT windowing toolkit and is installed by default by the operating systems officially supported by Synchrony 4.0. However, this library is often not included in newer releases of Linux and could be removed from a officially supported release by a system administrator.

Check in the Vantage log for any messages about libXp.so. To check whether this library is on the server:
  su
  find / -name libXp.so.6
  exit
If the library is present, make sure the folder containing the libary is included in your user''s environment variable LD_LIBRARY_PATH. If the library is not found, you will need to add it. This procedure varies by distribution. The procedure for RedHat is:
  su
  yum provides libXP.so.6
This will return the name of a package that contains the library, for example: libXp-1.0.0-15.fc12.i686. Using the package name yum found in place of {package} run:
  yum install {package}
  exit
Once the library is installed, stop Vantage and start it again.