using SXT lite 5 in 5ghz

Hello,
firstly I want to apologize for my limited knowledge about Mikrotik products and my english which is not very good. Here is the problem, i want to connect my sxt lite 5ac to an AP (omnitik5ac).
The AP is working, i am able to connect my laptop to the AP.
the Sxt is working normaly as a station connected to a 2.4ghz network using the quickset fonction and disabling the dhcp server.
But i am unable to connect to the 5ghz network of omnitik.
I see that 5ghz network is parameted in wlan2 interface, i’ve puted ssid and security profile in wlan2 settings but signal leds are all off.
Is there a procedure for this operation?
Which mode should i use for wlan config? are there any changes to be made in the section bridge/ports?
thanks a lot
Benoit

If it’s able to connect to a 2.4GHz network then it’s not an SXT lite 5..