I cannot insert bengali character in UTF8

I am using database with UTF8 and LC_CTYPE set as default value in
Postgresql 9.1.
But I cannot insert bengali character in a column.

Query Failed:INSERT into tracker (user_id, module_name, item_id,
item_summary) values ('1','Leads','353','বাংলা টেস্��...')::ADODB
error::->ERROR: invalid byte sequence for encoding "UTF8": 0xe0a62e

Item_summary is a text type column and we can insert japanese character in
this field.

Could anybody let me know what is the problem here?