Controllerless Networks

I want to divide the users into each category within a vlan and take the addresses from a separate pool

I had in my company all users take IP from one DHCP pool associated with VLAN 11

I created a new pool, called it pool12, and created vlan 12

So users connected to vlan 11 receive IP addresses from pool11

Users connected to vlan 12 receive IP addresses from pool12

The problem is when I convert the outlet connected between the controller and the access point to a trunk. Access point turns off!!!!

Now not enough info is provided, but lets try.

My assumption is that you are using tunneled connection between APs and controller and that vlan 11 is management and user vlan. 

Now you should add vlan 12 as tagged vlan on the controller's port and also tagged that vlan on the switch port where controller is connected.

In your screenshot you add vlan 12 as native. This would be ok, if this port is dedicated only for vlan 12 and you have vlan 11 on other port.

Best, Gorazd.