Signature not valid for master/sub account fund transfer

API Spot/Margin API
1

with my master API key (internal transfer enabled), I’ve tried these API to transfer USDT from master email to subaccount email, but none of them works. I got
{“code”:-1022,“msg”:“Signature for this request is not valid.”}
However, if I change destination email to master email (both fromEmail and toEmail are the same), it can work with some API. So the problem shouldn’t be signature mal-form. Is there anything I am missing?

https://binance-docs.github.io/apidocs/spot/en/#sub-account-futures-asset-transfer-for-master-account
https://binance-docs.github.io/apidocs/spot/en/#transfer-to-sub-account-of-same-master-for-sub-account
https://binance-docs.github.io/apidocs/spot/en/#universal-transfer-for-master-account

2

Signature for this request is not valid may be thrown due to you using the wrong secretKey to generate the signature. Note that if (For Sub-account) is stated in the API doc, you have to use the api and secret key of the sub account and use Master’s api and secret key if (For Master) is stated.

3

Let’s say I use this API endpoint:
https://binance-docs.github.io/apidocs/spot/en/#universal-transfer-for-master-account
with my master account API key and secret (internal transfer enabled)
I can transfer from MASTER SPOT Account to MASTER FUTURE Account without error,
but I can’t transfer from MASTER SPOT Account to SUBACCOUNT SPOT Account.
Any idea?