Calculated SecretHash is working for Singup and ConfirmSignup call but not working for InitiateAuth

[BakhtawarTradesmen]

STEPS

1. I am taking email and client secret id.
2. Concatenating them and then create HMAC of them.
3. Then I am taking base64 of it and sending it as SECRET_HASH.

hash_hmac('algo','concatenated string', 'COGNITO_APP_SECRET_HASH', true);

This php builtin function is used to calculate the HMAC.