[google-cloud-sql-discuss] App Engine phpmyadmin cannot connect to my Cloud SQL instance

Here's the tutorial I've followed:
https://cloud.google.com/sql/docs/mysql/phpmyadmin-on-app-engine

Once I deploy, I see the phpmyadmin index page, asking for me to log in. When I try, I get following messages:

Cannot log in to the MySQL server

mysqli_real_connect(): MySQL server has gone away
mysqli_real_connect(): Error while reading greeting packet. PID=-1
mysqli_real_connect(): (HY000/2006): MySQL server has gone away

this is what I used for my instance name
myprojectID:us-west1:mycloudsqlname

I can't figure out what I'm doing wrong. I tried the both version on the doc and the latest doc.
I tried to allow unsecure connections for Cloud SQL, didn't work.
App Engine authorization under "Connections" tab is checked greed - Apps in this project: All authorized.
I'm only using Private IP address, associated with "default" network setting.
Nothing on logs.

Can someone confirm that the tutorial above is working?
Any help would be appreciated.

--
You received this message because you are subscribed to the Google Groups "Google Cloud SQL discuss" group.
To unsubscribe from this group and stop receiving emails from it, send an email to google-cloud-sql-discuss+unsubscribe@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/google-cloud-sql-discuss/a950f4b1-0679-48bb-930b-2461cf527b68%40googlegroups.com.