ORDS, SODA & JSON in the Database

HI,
I installed ORACLE XE + TOMCAT 7 + ORACLE XE on windows XP.
All seems to work under debug session but on normal session I found the following message only when I put a specific parameter on my query.
The same query with the same parameter runs in the sqldev client whitout errors


Here below the massages:

HTTP Status 500 - System Unavailable. Please try again later.

type Status report

message System Unavailable. Please try again later.

description The server encountered an internal error (System Unavailable. Please try again later.) that prevented it from fulfilling this request.
Apache Tomcat/7.0.2


and in the log file:

2011-02-23 18:04:19 Commons Daemon procrun stdout initialized
APEX Listener version : 1.0.2.238.15.24
APEX Listener server info: Apache Tomcat/7.0.2
Using Config file:C:\Programmi\Apache Software Foundation\Tomcat 7.0\temp\apex\apex-config.xml
-- listing properties --
PropertyCheckInterval=60
ValidateConnection=true
MinLimit=1
MaxLimit=10
InitialLimit=3
AbandonedConnectionTimeout=900
MaxStatementsLimit=10
InactivityTimeout=1800
MaxConnectionReuseCount=50000

***********ERROR***********
init: # headers=46
declare nm owa.vc_arr := ?;
vl owa.vc_arr := ?;
begin
owa.init_cgi_env( ?, nm, vl );
htp.init; htp.HTBUF_LEN := 63;
? := sys_context('USERENV','SID');
end;
SID:18
CALL:
begin
f(p=>?);
commit;
end;
BINDS

p:106:3:4503262208013405:::::PAGE CALL:
declare
nlns number := 999999;
l_clob CLOB;
lines htp.htbuf_arr;
l_buff varchar2(32767);
l_clob_init boolean:= false;
l_file varchar2(5);
begin
OWA.GET_PAGE(lines, nlns);
if (nlns > 1) then
for i in 1..nlns loop
if ( length(lines(i)) > 0 ) then
if ( ( lengthb(l_buff) + lengthb(lines(i))) > 32767) then
if (NOT l_clob_init) then
dbms_lob.createtemporary(l_clob, TRUE);
dbms_lob.open(l_clob, dbms_lob.lob_readwrite);
l_clob_init:=true;
end if;
dbms_lob.writeappend(l_clob,length(l_buff),l_buff);
l_buff := lines(i);
else
l_buff := l_buff || lines(i);
end if;
end if;
end loop;
end if;
if (l_clob_init) then
dbms_lob.writeappend(l_clob,length(l_buff),l_buff);
l_buff := '';
end if;
? := l_clob;
? := l_buff;
if (wpg_docload.is_file_download) then l_file:='TRUE'; else l_file := 'FALSE'; end if; ? := l_file;
end;
get_page FAILED:ORA-06502: PL/SQL: errore : buffer della stringa di caratteri troppo piccolo di numero o valore
ORA-06512: a line 32

^^^^^^^^^^^^ERROR^^^^^^^^
ORA-06502: PL/SQL: errore : buffer della stringa di caratteri troppo piccolo di numero o valore
ORA-06512: a line 32


***********ERROR***********
init: # headers=46
declare nm owa.vc_arr := ?;
vl owa.vc_arr := ?;
begin
owa.init_cgi_env( ?, nm, vl );
htp.init; htp.HTBUF_LEN := 63;
? := sys_context('USERENV','SID');
end;
SID:18
CALL:
begin
f(p=>?);
commit;
end;
BINDS

p:106:3:3777982020408238:::::PAGE CALL:
declare
nlns number := 999999;
l_clob CLOB;
lines htp.htbuf_arr;
l_buff varchar2(32767);
l_clob_init boolean:= false;
l_file varchar2(5);
begin
OWA.GET_PAGE(lines, nlns);
if (nlns > 1) then
for i in 1..nlns loop
if ( length(lines(i)) > 0 ) then
if ( ( lengthb(l_buff) + lengthb(lines(i))) > 32767) then
if (NOT l_clob_init) then
dbms_lob.createtemporary(l_clob, TRUE);
dbms_lob.open(l_clob, dbms_lob.lob_readwrite);
l_clob_init:=true;
end if;
dbms_lob.writeappend(l_clob,length(l_buff),l_buff);
l_buff := lines(i);
else
l_buff := l_buff || lines(i);
end if;
end if;
end loop;
end if;
if (l_clob_init) then
dbms_lob.writeappend(l_clob,length(l_buff),l_buff);
l_buff := '';
end if;
? := l_clob;
? := l_buff;
if (wpg_docload.is_file_download) then l_file:='TRUE'; else l_file := 'FALSE'; end if; ? := l_file;
end;
get_page FAILED:ORA-06502: PL/SQL: errore : buffer della stringa di caratteri troppo piccolo di numero o valore
ORA-06512: a line 32

^^^^^^^^^^^^ERROR^^^^^^^^
ORA-06502: PL/SQL: errore : buffer della stringa di caratteri troppo piccolo di numero o valore
ORA-06512: a line 32


Could you kindly help me.
Thanks in advance for your help
Best Regards