Cannot read mysql directory , although I am member of mysql group

This is my mysql directory with rhe directory I want access to in bold (ie the database_name directory:

Code:drwx------ 6 mysql mysql 4096 Aug 23 18:38 .
drwxr-xr-x 33 root root 4096 Aug 15 13:05 ..
drwxr-x--- 2 mysql mysql 4096 Aug 15 08:15 database_name
-rw-r----- 1 mysql mysql 56 Aug 14 19:18 auto.cnf
-rw------- 1 mysql mysql 1676 Aug 14 19:18 ca-key.pem
-rw-r--r-- 1 mysql mysql 1112 Aug 14 19:18 ca.pem
-rw-r--r-- 1 mysql mysql 1112 Aug 14 19:18 client-cert.pem
-rw------- 1 mysql mysql 1680 Aug 14 19:18 client-key.pem
-rw-r--r-- 1 root root 0 Aug 14 19:18 debian-5.7.flag
-rw-r----- 1 mysql mysql 292 Aug 23 18:37 ib_buffer_pool
-rw-r----- 1 mysql mysql 12582912 Aug 23 18:38 ibdata1
-rw-r----- 1 mysql mysql 50331648 Aug 23 18:38 ib_logfile0
-rw-r----- 1 mysql mysql 50331648 Aug 14 19:18 ib_logfile1
-rw-r----- 1 mysql mysql 12582912 Aug 23 18:38 ibtmp1
drwxr-x--- 2 mysql mysql 4096 Aug 14 19:18 mysql
drwxr-x--- 2 mysql mysql 4096 Aug 14 19:18 performance_schema
-rw------- 1 mysql mysql 1676 Aug 14 19:18 private_key.pem
-rw-r--r-- 1 mysql mysql 452 Aug 14 19:18 public_key.pem
-rw-r--r-- 1 mysql mysql 1112 Aug 14 19:18 server-cert.pem
-rw------- 1 mysql mysql 1680 Aug 14 19:18 server-key.pem
drwxr-x--- 2 mysql mysql 12288 Aug 14 19:18 sysI am a member of mysql:

Code:robertw@bananapi:~$ id
uid=1000(robertw) gid=1000(robertw) groups=1000(robertw),5(tty),6(disk),20(dialout),27(sudo),29(audio),33(www-data),44(video),46(plugdev),60(games),100(users),101(systemd-journal),104(input),108(netdev),112(ssh),113(mysql)However, when I do this:

Code:robertw@bananapi:~$ ls -all /var/lib/mysqlI get this message:
Code:ls: cannot open directory '/var/lib/mysql': Permission deniedIs it not thae case that this:

Code:drwxr-x--- 2 mysql mysql 4096 Aug 15 08:15 database_nameIs this not saying the group members have read and execute permissions?

Can anyone shed any light on why I can't read the contents of the directory please?

Many thanks