Problems with MapServer

[Stefano Casagrande (I&S)]

Hi!

I have installed MapServer 1.0.2, MapServerWebExtensions 1.0.2 and 
everything's ok.

In fact the example application

http://localhost/mapguide/phpviewersample/ajaxtiledviewersample.php

Works. Even if I change the ajaxtiledviewersample.php with a new $webLayout 
and $mapDefinition it shows the new map.

But if I develop another application with the same map that works with the 
example it tell me:

Failed to retrieve message for "MgFileNotFoundException". Exception occured 
in method ByteSourceFileImpl.LoadFile at line 126 in file 
c:\build_tux_area\mgdev_opensource\common\service\data\ByteSourceFileImpl.cpp

WebConfig.ini is ok, what should I check ? How should I found what fails ?