oracle to_char() different language shows garbage - sql

Question

In my oracle function there is a query that is used to make an XML output with the required values. Everything works fine. If I store a Bengali/Bangla name in a column then it returns to my website perfectly, but the problem arises when I want to see the date in Bengali/Bangla. The following query has 2 columns as date. I have used to_char() to format them.
SELECT XMLAGG(XMLElement("employee",
XMLForest(bp.ebasp_id AS "ebasp_id",
bp.b_ebasp_name AS "ebasp_name",
bp.ebasp_gender AS "ebasp_gender",
bp.ebasp_category AS "ebasp_category",
bp.ebasp_region_type AS "ebasp_region_type",
bp.ebasp_region_name AS "ebasp_region_name",
bp.ebasp_sub_region AS "ebasp_sub_region",
bp.ebasp_location AS "ebasp_location",
bp.b_ebasp_designation AS "ebasp_designation",
to_char(bp.ebasp_date_of_joining,'DD-MM-YYYY','NLS_DATE_LANGUAGE=bangla') AS "ebasp_date_of_joining",
bp.ebasp_grade AS "ebasp_grade",
bp.ebasp_slab AS "ebasp_slab",
bp.ebasp_basic AS "ebasp_basic",
bp.ebasp_photo_upload AS "ebasp_photo_upload",
to_char(bp.ebasp_created_on, 'DD-MM-YYYY HH:MI:SS AM','NLS_DATE_LANGUAGE=bangla') AS "ebasp_created_on",
bp.ebasp_created_by AS "ebasp_created_by")))
INTO xmlReturn
FROM tbl_emp_basic_profile bp
WHERE bp.ebasp_designation=sent_designation
The returned date value is : 07-02-2016 03:43:29 ������
This value is shown in Mozilla. But name shows perfectly in Bangla. What is the problem? Besides, I have tried using to_nchar();