Oracle Database Discussions

I am using Oracle 11g 11.1.0.7 on a Windows 2008 server in spanish_peru

This is what comes up when I run the select * from nls_database_parameters

PARAMETER
------------------------
VALUE
------------------------
NLS_LANGUAGE
AMERICAN

NLS_TERRITORY
AMERICA

NLS_CURRENCY
$


PARAMETER
------------------------
VALUE
------------------------
NLS_ISO_CURRENCY
AMERICA

NLS_NUMERIC_CHARACTERS
.,

NLS_CHARACTERSET
WE8MSWIN1252

However, I have the nls_language set to latin american spanish and the nls_territory set to peru.
I have checked the DB Control and it shows the initialization parameters as such but the nls_database_parameters does not.

I do an Oracle Text search something like this:
select score(1)Relevancia,
dbms_lob.getlength("TRANS_DOCUMENTO") "TRANS_DOCUMENTO",
FILENAME, TRANSCRIPCION_ID,
ctx_doc.snippet
('TRANSCRIPCION_DOC_CTXIDX',
TRANSCRIPCION_ID,
:P20_SEARCH,
'<span style="color:darkgreen;font-weight:bold;font-size:14px;">',
'</span>') "Fragmento de Código"
from transcripcion_documentos
where contains(trans_documento, :P20_SEARCH, 1) > 0
and creado_fecha between (to_date(:P20_PREVIOUS, 'dd/MM/yyyy')) and (to_date(:P20_NEXT, 'dd/MM/yyyy'))
order by 1 desc

It will not return any data. I remove the following line:
and creado_fecha between (to_date(:P20_PREVIOUS, 'dd/MM/yyyy')) and (to_date(:P20_NEXT, 'dd/MM/yyyy'))
and the results are shown.

Any ideas as to how to change this script to return data. I have tried without the to_date statement and still no data is returned. Is there any issue with the nls_database_parameters showing one thing and the init parameters showing another.

Is there some type of Alter system script that changes these parameters? Although making sure the nls_language and nls_territory were listed in the pfile and spfile should have been good enough.
Any ideas as to what to try next??