The path used in the admin/aprsd.conf file is wrong as the correct path should be APD225 (or in general APDxxx, where xxx is the version of aprsd). This is what the official APRS protocol specification mandates.
The modification required is as follows:
--- aprsd-2.2.5-15/admin/aprsd.conf 2003-10-01 18:57:16.000000000 +0200
+++ aprsd-2.2.5-15-modified/admin/aprsd.conf 2010-07-14 19:42:23.004151825 +0200
@@ -73,7 +73,7 @@ expire 35
#This is only used when using Linux sockets, not the TNC.
#For the TNC, set this in INIT.TNC. Note the format is
#slightly different to the TNC command.
-aprspath APRS v WIDE
+aprspath APD225 v WIDE
#
# Allow Internet to RF message passing.
Patch for the correct path in aprsd.conf