i cannot access the cloud sql(mysql) using private ip on vpc, then this message show.

ERROR 1045 (28000): Access denied for user 'root'@'10.146.15.196' (using password: YES)

i have confirmed the following items.

• use unix socket of cloud proxy, i can access and login with the same username and password (check username and password)
• In the user table of the msql database, root is host:% (check mysql allow ip)
• The request is being made using cloud logging (request can arrives)
• Connection test passes https://cloud.google.com/network-intelligence-center/docs/connectivity-tests/how-to/running-connectivity-tests (configuration is correct)
• use private ip of connect with tcp of cloud proxy, then i can login (check connect with tcp, and private ip)
• create another cloud sql instance same region then i can login this instance using private ip. (check region problem)

What's wrong?