Problems of ip assignment with MR42 in bridge mode

[Prisma]

I have configured a port in trunk mode on a cisco 2960 switch, this connects to the AP MR42. When generating the SSID and configure it in bridge mode. The MR42 APs take IP from the administration vlan (55), but when connecting a host to the AP (passing through the association process) it does not deliver IP from the internal servers that deliver the DHCP configured for the other VLANs. I need to know if this is a configuration problem in the SSID?. Thanks for your reply

Configuration SW

interface GigabitEthernet1/0/21
description AP-PRUEBA
switchport mode trunk
end

Configuracion de AP MR42

[PhilipDAth]

You haven't configure VLAN tagging (in the screen shot).  So they will be dropped into the native VLAN.  Is that correct, or should you be putting them into another VLAN?

[Prisma]

No, The native vlan is for default (1). The other vlans not tagging here. But change my configuration, only permitted the other vlans (with command allowed). Attachment the configuration.
interface GigabitEthernet1/0/21
description AP-PRUEBA
switchport trunk allowed vlan 1,55,20
switchport mode trunk
end

My questions are:
1.-should be configuration the native vlan (switchport trunk native vlan 55) and allowed the others vlans (switchport trunk allowed vlan 1,20). For the host receive IP of the DHCP (DHCP vlan 20)?

2.Should be configuration additional configuration on SSID? Tagging vlan option?

Thks for you reply

[MRCUR]

You need to configure VLAN tagging in Dashboard (on the screen where you took the screenshot) as @PhilipDAth mentioned. 

Your switch port config looks fine assuming you're using VLAN 55 for management and 20 for clients (once you configure this on the SSID). 

[Adam]

Agreed with the above assessment.  If you don't have vlan tagging enabled then it'll just use the default vlan or whatever you have setup for the vlan on the AP interface.