Using si4460 (with RH_RF24 Library) at 868Mhz

Hi, I have two devices that transmit and receive correctly at 434Mhz. But do not work at 868Mhz.

i'm using the Si4460 transceiver and RH_RF24 Library. In the init function of the LibraryI changed this line:

//setFrequency(434.0); setFrequency(868.0);

need some other changes?