i have that mini mono but in red and put 27mhz radio in it, the only thing i can think of is re-binding, if you have the bind plug (disconecct the motor leads and servo)

1- put it in the bind port
2- connect battery to the esc
3- switch on transmitter
4- if it has a bind button then press it
5- once all lights are steady remove bind plug immediatly