problem with superchannel

i have a rb with 3.0rc13 and superchannel license. He works in client mode. On AP is version 2.9.50 and he works on 5400 MHz. Does anyone know why I cant connect rc13 on 2.9.50 with that frequency?

you have to enter this frequency in the ‘scan-list’ of the client. now you have “scan-list=default-ism”, change that to “scan-list=default-ism, 5400”

thus very large, it working on v2.9.48, i.e. you even don’t need v3.xx version