QQ NT Windows database decryption passphrase not working

[lavmaharjan]

The error message:
sqlite> .open nt_msg.clean.db
sqlite> pragma key = "################"; pragma kdf_iter = "4000";
ok
sqlite> attach database "nt_msg.db" as plaintext key ""; Select sqlcipher_export("plaintext"); Detach database plaintext;
Parse error: file is not a database (26)
sqlite>

When trying with DB Browser SQLCipher, the settings kept are shown in the image below.

This is also not working to open nt_msg.db even after cleaning it by removing 1024 characters.