Querying Unicode (Arabic) Column

Question

I have problem in querying on Arabic field which is stored in a column of type nVarchar2
The column is populated properly through c# program. The Arabic data is retrieved and presented properly.
The problem is when I Query the Column.
My query looks like
SELECT BookID , BookTitle FROM books WHERE author_ar like ‘%فيكتور%’
SELECT BookID , BookTitle FROM books WHERE author_ar like ‘xxx%’ (xxx being a Unicode input)
This query those not yield any results. However when I substitute the “like” operator with the “=” operator the search return the expected row.
N/B I am using Oracle 10 g release 2
     PARAMETER     VALUE
1     NLS_LANGUAGE     AMERICAN
2     NLS_TERRITORY     AMERICA
3     NLS_CURRENCY     $
4     NLS_ISO_CURRENCY     AMERICA
5     NLS_NUMERIC_CHARACTERS     .,
6     NLS_CHARACTERSET     WE8MSWIN1252
7     NLS_CALENDAR     GREGORIAN
8     NLS_DATE_FORMAT     DD-MON-RR
9     NLS_DATE_LANGUAGE     AMERICAN
10     NLS_SORT     BINARY
11     NLS_TIME_FORMAT     HH.MI.SSXFF AM
12     NLS_TIMESTAMP_FORMAT     DD-MON-RR HH.MI.SSXFF AM
13     NLS_TIME_TZ_FORMAT     HH.MI.SSXFF AM TZR
14     NLS_TIMESTAMP_TZ_FORMAT     DD-MON-RR HH.MI.SSXFF AM TZR
15     NLS_DUAL_CURRENCY     $
16     NLS_COMP     BINARY
17     NLS_LENGTH_SEMANTICS     BYTE
18     NLS_NCHAR_CONV_EXCP     FALSE
19     NLS_NCHAR_CHARACTERSET     AL16UTF16
20     NLS_RDBMS_VERSION     10.2.0.1.0

Answer 1

Here is another scenario
I realized this
When i use PL/SQL Developer
The Unicode data is entered in the form inverted question marks ¿¿¿¿¿
actually it is representation i think when the Oracle interface cant find the character.
However when i run the query it return me the correct row.
So am bit sure i am missing Unicode or nvarchar2 representation Character set.
Hope this a valid assessments and will narrow down my problem :)
Regards Hratch