Hello, my situation is the next:

I can access to manage 10.23.3.243 bridge since 10.23.3.99 and is impossible to manage 10.23.3.242.
Two bridges are the same configuration.
Nobody can help me?
Thanks.
A peek at your exact configuration might help…
I have followed the configuration proposed in mikrotik wiki creating the vlan99.
http://wiki.mikrotik.com/wiki/Manual:Switch_Chip_Features
Is cpu port member of VLAN50 on 10.23.3.242?
You say this configuration?

Maybe this will help:
Wiki says:
Configure the port which connects switch-chip with CPU, set “vlan-header=leave-as-is” because management traffic already should be tagged
and
Since the master-port receives all the traffic coming from switch-cpu port, VLAN has to be configured on master-port, in this case “ether2” port
In your screenshot ether2 has “slave” in its name. Like Sob said , export your switch configuration. It will tell us where the problem could be. Like this its just blind guessing.
I attach the backup files of switchs. I changed the extension .backup for .txt.
10-23-3-242.txt (48.5 KB)
10-23-3-243.txt (48.3 KB)
From New Terminal type export and copy-paste here.
Quick look into your configuration and i can see you did not set Admin MAC for bridge.
Please set admin MAC to bridge infterface on both switches.
But I dont know why you even created a software bridge as you only added ether1-master interface in this bridge?
I would remove bridge and add VLAN50 interface (/interface vlan add) ontop of ether1-master-local
Also add switch1-cpu to VLAN table:
/interface ethernet switch vlan add ports="switch1-cpu" vlan-id=50
/interface ethernet switch egress-vlan-tag add tagged-ports="switch1-cpu" vlan-id=50