The problem with maxscale for multi-master cluster

Hello.

I have 2 mysql servers with multi-master replication.

And i need use maxscale.

My config:

[maxscale]
threads=auto

[db1]
type=server
address=172.31.6.70
port=3306
protocol=MariaDBBackend

[db2]
type=server
address=172.31.6.71
port=3306
protocol=MariaDBBackend

[PerconaDB-Monitor]
type=monitor
module=mariadbmon
servers=db1,db2
user=maxscale
password=5D68B4AA55F84B754DDEB891CE7A2180
monitor_interval=1000
detect_stale_master=true

[Read-Write-Router]
type=service
router=readwritesplit
servers=db1,db2
user=maxscale
password=5D68B4AA55F84B754DDEB891CE7A2180
enable_root_user=1

[MaxAdmin-Service]
type=service
router=cli

[MaxAdmin Listener]
type=listener
service=MaxAdmin Service
protocol=maxscaled
port=6603

[Read-Write-Listener]
type=listener
service=Read-Write-Router
protocol=mariadbclient
port=3306

When i run the command - maxadmin -pmariadb list servers

I see

db1 | 172.31.6.70 | 3306 | 0 | Running
db2 | 172.31.6.71 | 3306 | 0 | Running

None of the servers is a master

And in logs i see:

error : [readwritesplit] Couldn't find suitable Master from 2 candidates.

When i stop 1 servers in my multi-master cluster, maxscale at once sees master and everything is ok

db1 | 172.31.6.70  |  3306 | 0 | Master, Running
db2 | 172.31.6.71  |  3306 | 0 | Down

Why do i get error when 2 masters is online?

Could you help me?